Close Program/Task Manager
This is NOT a list of tasks/processes taken from Task Manager or the Close Program window (CTRL+ALT+DEL) but a list of startup applications, although you will find some of them listed via this method. Pressing CTRL+ALT+DEL identifies programs that are currently running - not necessarily at startup. For a list of tasks/processes you should try WinTasks 5 Standard/Professional from LIUtilities or the list at AnswersThatWork. Therefore, before ending a task/process via CTRL+ALT+DEL just because it has an "X" recommendation, please check whether it's in MSCONFIG or the registry first. An example would be "svchost.exe" - which doesn't appear in either under normal conditions but does via CTRL+ALT+DEL. If in doubt, don't do anything.

Operating System Differences
A number of entries are repeated due to the way that different operating systems display startup items. For example, WinMe lists "POPROXY.EXE" as "Norton eMail Protect" in both MSCONFIG and the registry whereas WinXP lists it as "Poproxy" in MSCONFIG and "Noeton eMail Protect" in the registry.

To avoid the list becoming too large, all VIRUSES are shown using the registry version which is common to all Windows versions.

Alternatively use your browsers search facility - Ctrl+F for IE users.

Key:

"Y" - Normally leave to run at start-up
"N" - Not required - typically infrequently used tasks that can be started manually if necessary
"U" - User's choice - depends whether a user deems it necessary
"X" - Definitely not required - typically viruses, spyware, adware and "resource hogs"
"?" - Unknown

Use your browsers search facility - Ctrl+F for IE users.

X	S0undMan	svch0st.exe	Added by the LOVGATE.AB WORM!
?	S24EvMon	S24EvMon.exe	Event Monitor - supports driver extensions to NIC Driver for wireless adapters. Is it required?
X	S3 Internal Chip	s3serv.exe	Added by the AGOBOT-DD WORM!
?	S3apphk	S3apphk.exe	S3 graphics related?
?	S3Hotkey	s3hotkey.exe	S3 Video driver related. What does it do and is it required?
?	S3Mon	S3Mon.exe	S3DuoVue multi-monitor taskbar helper by S3 Graphics. What does it do and is it required?
N	S3TRAY	S3Tray.exe	S3 display configuration taskbar utility for S3 chipset based graphics cards. Can be run from Start-> Settings -> Control Panel -> Display
?	s3tray2	s3tray2.exe	Same as the s3tray entry in this table?
?	S3TRAYHP	S3trayhp.exe	S3 Video driver related. What does it do and is it required?
U	S4F	S4F.exe	S4F internet filtering software
X	s4helper	s4helper.exe	Searchcentrix hijacker
?	SA	Sa3.exe	Logitech QuickCam driver. Is it required?
?	SA Service	SAservice.exe	Associated with Cyber Trio and Warner troubleshooting software from G-Tek Technologies and pre-installed on some Packard Bell and NEC PCs. What function does this perform and is it required?
N	Sa3dsrv	Sa3dsrv.exe	3D sound extension for Windows
X	saap	saap.exe	180Solutions/N-Case adware variant
N	Sabreserver	SABSERV.EXE	Airline reservation software from Sabre. Available via Start -> Programs
N	SAClient	RegCon.exe	AT&T or ComCast BBClient - monitors system and network-delivered services for availability. Your current network status is displayed on a color-coded web page in near-real time. When problems are detected, you're immediately notified by e-mail, pager, or text messaging
X	Safe	SafeWin.exe	Added by the FOCOSENHA TROJAN!
X	SafeGuard Popup Blocker Updater	regsvr32 [path] sfgupd.dll	SafeguardProtect/Veevo hijacker
X	SafeGuard Popup Blocker Updater (required)	regsvr32 [path] sfg****.dll [* = ramdom char/digit]	SafeGuard Protect/Veevo - hijacker
X	SafeGuard Popup Updater (required)	regsvr32 [path] sfg****.dll [* = ramdom char/digit]	SafeguardProtect/Veevo hijacker
X	SafeGuard Popup Updater (required)	regsvr32 [path] PDF****.dll [* = random char/digit]	SafeguardProtect/Veevo hijacker
N	SafeInstall.exe	SAFEIN~1.EXE	Monitors a download and ensures an newer version of a file isn't replaced by an older one
N	SafeOFF	SafeOff.exe	Provides protection that if user accidentally presses the power switch a dialog will pop up for confirmation
X	SafeSearch	safesearch.exe	AutoSearch parasite variant
X	SafeSurfingUpdate	SSUpdate.exe	DyFuCa/MoneyTree parasite variant
U	Safeworld	Freedom.exe	SafeWorld Internet Security
X	Sagate Security Firewall	sagate.exe	Added by the GAOBOT.BOW WORM!
N	SAgent2ExePath	SAgent2.exe	Seiko Epson printer status agent. Disable if printer is not used often
U	SAGENTSERVICE	Sagent.exe	Added by TinySpyAgent Note - this application must be manually installed
X	sagnt	sagnt.exe	Adware web downloader
X	SAHagent	Sahagent.exe	ShopAtHomeSelect parasite
X	SAHBundle	bundle.exe	ShopAtHomeSelect parasite related
X	saie	saie.exe	180Solutions/N-Case adware variant
U	SAIMON	SaiMon.exe	Saitek joystick driver
X	sain	sain.exe	180Solutions/N-Case adware variant
X	sais	sais.exe	180Solutions/N-Case adware variant
?	SaiSmart	SaiSmart.exe	"Smart Button Special Sauce" - included with the latest software for Saitek game controllers. Related to the "S", "Shift" or "Smart" button. What does it do and is it required?
U	SaitekAutoConfigure	saicnfig.exe	Configuration for Saitek game controllers
X	salm	salm.exe	180Search adware
X	salm	salm.exe	180Solutions/N-Case adware variant
U	SAMcal	SAMcal.exe	SamCal - calendar/reminder program
U	Sametime Connect	Connect.exe	IBM Lotus Instant Messaging and Conferencing software
N	SandIcon	SandIcon.exe	SanDisk ImageMate CompactFlash card reader SDDR-31 (USB). Very little use except to place the Sandisk icon beside its drive designation in Windows Explorer. The reader itself will work fine without it. The simplest thing is to just unplug the reader when you're not using it. It may slow the startup by a few nanoseconds, but once the software sees there's no reader, you get back the resources
X	sapp	sapp.exe	180Solutions/N-Case adware variant
X	saSyncMgr	rundll32.exe sasync.dll, SyncWait	Browser hijacker - redirecting to Searchant.com
U	SATARaid	SATARaid.exe	RAID driver for serial ATA disks on some motherboards such as the DFI Lanparty range. Only loaded if one is using RAID support on SATA drives
X	satmat	satmat.exe	Transponder parasite updater/installer
U	SAUpdate	SAUpdate.exe	Big Brother from Quest Software. System and network monitor
Y	SAVAgent	SAVAgent.exe	Part of Sophos anti-virus software. Required for centrally administered Sophos updates to work correctly, e.g. automatically updating PCs used by dial-in home or out-of-office users
X	Save	Save.exe	SaveNow adware
X	SaveDate	SaveStartDate.Exe	Unidentified adware
X	Savenow	SaveNow.exe	SaveNow adware
X	Savenow	savenow.exe	Added by the SPREDA.B VIRUS!
U	Say The Time 5.0	SAYTIME.EXE	This program has audio cues for the system clock in male and female voices, customizes the appearance of the system clock, and can synchronize it to a time server regularly
U	SB	SB.exe	Acer Soft Button on Acer Tablet PCs
N	SB Audigy 2 Startup Menu	/l:eng	Related to the Dell OEM version of the Sound Blaster Audigy 2 sound card. If this item is listed and checked in startup, the System32 Folder will appear on every startup. A patch is available - filename R75304.EXE - that fixes the issue. You can find that file at support.dell.com by typing that name in the 'Search' box available there. It addresses the root of the problem in Creative's software and corrects it. Unfortunately there is no direct link to the file, but it's easily available using the search function
X	SB Watchdog	SBWatchdog.exe	Spyware utility installed by the manufacturers of some laptops (Sony) used to monitor browsing habits and send them back to whoever installed it - released by SoftBank. See here for more information
U	SBAutoUpdate	sbautoupdate.exe	SpywareBlaster auto-updater
U	SBC Self Support Tool	matcli.exe	matcli.exe is a motive Assistant Command line interface that gathers information about your system's identity like your name email address, city, county, etc and gets written to a log file. The SBC Self Support Tool is required to run with the Help and Support program. If you uncheck SBC and and then run Help and Support it will add another SBC entry in the startup menu. If you remove this software in "add/remove programs" some help menus in help and support will not be available. You decide
U	SBDrvDet	SBDrv.exe	Detects the "Easy Front-Panel Audio Connectivity Drive Internal Drive Bay" on the Sound Blaster Audigy 2 Platinium eX. Can be disabled if you don't have one
X	SBHC	sbhc.exe	SuperBar parasite - uninstall available here
N	SBMX	sbmx.exe	SoundMAX MPU401 MIDI device emulator for x86 VM DOS games/apps (for Win9x only)
U	SbUsb AudCtrl	RunDll32 sbusbdll.dll, RCMonitor	Control for Soundblaster MP3 external (USB) sound card
N	sc	scrubxp.exe	ScrubXP - utility that deletes safe to remove files, cookies, browsing history, etc
U	sc	sc.exe	Watchdog 2.0 Software - monitoring program
U	sc	run.exe	All-In-One_SPY stealth monitoring software - allows monitoring and recording of all actions performed on a computer. It records all keystrokes, remembers addresses of Internet pages visited, and maintains a log file listing all applicationsrun on the computer. It can create screenshots and record sounds from the computer's microphone to a sound file
?	sc23exec	sc23exec.exe	Possibly related to a digital camera
Y	SC3300CC	SC3300CC.exe	SiPix digital camera Twain device driver
X	scan	mscman.exe	Spyware/malware, included into the latest version of Grokster, among others. According to research by SpyBot's PMK,  "able to trick ZoneAlarm, auto-clicking it to allow passing through the firewall!"
?	Scan Detector	Pmxdetect.exe	Associated with PrimaScan scanners. Is it required?
?	Scan Wizard	button.exe	Associated with ScanWizard as supplied with Microtek scanners - see also Scanner Detector or SDetect. What does it do and is it required?
X	ScanDisk	ScanDisk.exe	Added by the GANDA.A WORM! Note - this is not the valid "ScanDisk" Win9x/Me standard disk error checker
X	scands32.exe	scands32.exe	Added by a variant of the Adclicker TROJAN!
?	ScanFile	??	??
?	ScanInicio	Inicio.exe	Part of Panda Anti-Virus. Responsible for scanning the boot sector of your disk and your memory at startup to check for viruses that try and load and act before your anti-virus is fully operational. It only adds a fraction of a second to start-up time and is worth leaving active
N	Scanner Detector	SDetect.exe	ScanSuite Scanner Detector - part of ScanWizard, supplied with Microtek scanners. Waits until you press the "GO" button and seems to serve no other purpose. Automatically installed without prompting. Not required if you can start your scanning application before pressing the "GO" button
X	Scanreg	[filename]	Added by the QQPASS.E TROJAN!
X	ScanRegistry	nsrvnt.exe	Added by the NERTE TROJAN!. Not to be confused with the real ScanRegistry - which is a vital Windows file. This version has the executable as nsrvnt.exe not scanregw.exe
X	ScanRegistry	scanregv.exe	Added by the MASTERLOCK TROJAN!. Not to be confused with the real ScanRegistry - which is a vital Windows file. This version has the executable as scanregv.exe not scanregw.exe
Y	ScanRegistry	Scanregw.exe	Scans the system registry and makes back-ups at start-up. Important should the registry become corrupt. The executable "Scanregw.exe" is located in %windir% (where %windir% is the Windows directory - C:Windows or C:Winnt)
X	ScanRegistry	Scanregw.exe	Added by the STATOR WORM! Not to be confused with the legitimate ScanRegistry entry - which is a vital Windows file. The executable "Scanregw.exe" is located in %windir%System (where %windir% is the Windows directory - C:Windows or C:Winnt). Runs from the registry RunServices key as opposed to the Run key
X	ScanSpyware v *	Scanner.exe	Spyware remover (where * = the version number) of dubious repute, see this list of Rogue/Suspect Anti-Spyware Products & Web Sites