It is time to decide reset your hard drive:
1 .- seek installation diskette and reboot the computer from 0.
2 .- install programs favorites, the first time takes morecomplicate because you must download all the software packages that you like,
Messenger, acrobat reader, fire fox, google acelerator, windows media 11 etc etc etc..
Save all these installers in a folder named backup, after that you reset computer allways be easy.
3 .- defragments your hard drive
4 .- the most important thing is to install the fire fox and google acelerator.
5 .- try not to see porn sites on your computer games jejejeje.
6.- Researching on the Internet to optimize the performance of the game, which values video sound so you must adjust, there are many pages that talk about this point.