Skipping Mouse?

Hey

recently i had to reformat my laptop because a nasty virus had got hold of it, i didnt seek to fix it because reformatting helped me clear all the crap off my laptop anyway

however to the point

since reformatting my pc, my mouse now seems to judder and skip across the screen, programs run slower, movies skip

i mean, i installed and updated all the drivers again and my laptop is by no means low spec

2.0GhZ Centrino Duo
Geforce 8600GT gfx card
2GB ram

so i dont understand why im getting these display problems

any fixes? thanks