Computer Problems: Need help

Don't buy a new monitor. It's not your monitor, and I'd bet you $4000 that your monitor is not causing that particular problem.

It's most likely your video card. What you should try first is download new drivers. If that doesn't help, try reaseating it. Open your computer, unscrew the video card, take it out, (blow on it if you want,) then put it back in, and screw it in.

If that doesn't fix it, then something is most likely wrong with your actual card. That means you have to try another card. If you have onboard video, try that. If not, borrow an AGP card from a friend and try it. If your screen is still crappy like that, then your AGP slot is messed up. Try a PCI Video card (if any of your friends have slightly older computers with non-AGP cards). There's a 99% chance that will work. Remember to download drivers for each new card you try too.