Or windows for that matter? I just upgraded video card from ati 9800 pro 128mb to ati x800 XL 256mb. And i'm looking to buy a 3.6 ghz, i think with both these components i'll see a substantial increase in performance and visual quality. What do you think? Thanks!

Yes, you should see a pretty substantial improvement with both upgrades.As for a reinstall, it should not be necessary, especially since you are not changing video card manufacturers (thus no change of video drivers) nor your motherboard. Having said that, I tend to reinstall every time I make an upgrade so that I can rerun benchmarks and ensure that I squeeze every last millisecond out of my new hardware. You may not believe the improvement is worth the effort. The choice is yours.Enjoy your upgraded rig!Edwin