Tip1 : It is good to keep the size of the C driver bigger than other slave drives, because the center part of the spiral magnet of hardisk can give more read speed then the outer part of the spiral.
Nah! I don't buy that. That might have been true 20 years ago, but not today with today's drives. And besides, it assumes the data is stored closest to the spindle.
When using multiple drives, I recommend the smaller as the boot drive, keeping only the OS and hardware drivers on it, and installing all your programs and data files on the slaves.
@aly - your dump shows Norton AntiVirus Version 126.96.36.199 and Norton 360. Do you have both installed and running or are they the same? While Norton has made tremendous improvements over the years, it is still a resource hog. I personally use and recommend Microsoft Security Essentials (MSE)
and Windows Firewall with my 64-bit Windows 7 system with no regrets.
Increasing your RAM to 8Gb would help but I don't see a graphics card listed which makes me think you are using integrated graphics. If that is the case, I would consider adding a better graphics solution first.
The downside there, however, is graphics cards are often the most power hungry device in our systems. So, a new PSU may be needed to support a new card.
This all assumes your system is not being bogged down with spyware and other clutter, and too many things being started when Windows starts. If it used to run fine and no longer does, then adding more hardware may not be the solution.