Yah, for a long time I've been plagued with ugly colored streaks whilst playing games on my geforce4 mx440 (PCI interface) with windows XP and Abit KT7A-RAID mobo. It looks like a huge chunk of the wall would just be sticking out in some games, while in others these colored squares would just appear out of nowhere. I know that I've searched through about a gross dozen of websites, browsing through countless forums, trying to find other people who might have a solution. I've heard that with the AGP interface they could change the voltage settings to fix it, (but you can't do that for PCI interfaces very easily), that some people even went so far as to cram a piece of wood (yes, from a tree) into their computer to change the shape of the card. I tried overclocking, underclocking, over 20 different drivers (leaked, official, WHQL, Omega, Forceware/detonater) to no avail. I flashed my mobo's bios to the newest version, didn't work. But finally, FINALLY, I found a way. It is a pretty simple solution, but yet a lot of people haven't done it... just flash the video card's BIOS!
 
http://whitebunny.demon.nl/hardware/chipset_nvidia.html
 
That link conatins all the tools you need. Any questions about how to flash video BIOS... ask someone else, this post is long enough as is.