problems with low frame rates?

[Dakotakid44]

a guy I know recently put it in a 6600 GT and is getting worse frame rates than with an ATI 9200. I am confused because the 6600 is a step up from the 9200. Here is his set up:

CPU = AMD athelon 1800+
Ram = 1 gb patriot series
Gfx = That 6600gt
Sound = Sound Blaster Live!
VIA KT600 Chipset Based KT6V Series
Windows XP

I had him update video drivers, he could not find the right bios to update his computer. I would appreciate some help!