Actually, if you want EVERYTHING gone, you assure you have your reinstall disk ready for Windows XP, and you run a drive wiping program that runs passes of 0's or random numbers over the drive, and boot from the CD and reinstall Windows. Just reinstalling Windows isn't as effective. However, I don't reccomend wiping the computer. Have you taken the simple steps?:
1)Download and Run CCleaner:
-Download CCleaner
-Run Cleaner with all checked
-Run Registry with all checked
2)Download and run Auslogics Disk Defragmenter
-Download and let it run on your drive
3)Uninstall old programs
-Yes
4)Delete unused desktop icons
-Hey, it's a good habit =P
5)Install and use Google Chrome =P
At least do the first 2, they're a definite help, and require no prior knowledge or much effort.
More advanced, you can:
1)Run msconfig
-Start>Run
-type "msconfig"
-Goto startup
-Look after the last slash in the Location column to find the name
-look it up on
http://www.processlibrary.com/
-If it says it's unecessary, and you feel you don't want it, disable it
Hope I helped?,
Sp133n!