power down problem

[animonster]

A while back I formatted my hard drives to clean up all the extra junk laying around. Since then, my motherboard and hard drives will not power down after Windows shuts down (It hangs at a black screen). Here are my specs:

-Tyan Tomcat K8E (S2865) motherboard
-AMD Athlon 4400+ X2 dual core processor (2.2GHz, 1mb + 1mb L2 Cache)
-Kingston 2GB 400MHz DDR Non-ECC CL3 (3-3-3) DIMM
-Sound Blaster Live 24-bit sound card
-Nvidia Quadro FX 540
-Thermaltake PurePower 460W ATX 12V 2.2 Blue Light
-Western Digital Raptor 36.7GB 10,000RPM SATA150 HardDrive x2 on RAID 0
-PS/2 keyboard, USB mouse, USB wacom tab.
-Windows XP Professional

-I have updated my BIOS and processor drivers to the latest
-I have made sure that Windows has SP2 and all of the latest updates
-I have tried all ACPI HAL settings...none work (it is ACPI multiprocessor now)
-In my BIOS, I have the default ACPI setting: Enabled, allow for S1&S3
-I tried to make sure APM was enabled on the APM tab of Power Options in the Control Panel, but there is no APM tab.
-I tried to enable the NT/ACPI Legacy Node in the Device Manager, but it is not there either.

Any suggestions as to how I can get my computer to properly power down...like it used to?