Maybe you've already resolved this issue, but I have a similar setup with the same problem -- Recently installed Win XP Home on a Gateway Performance 1800 CX with a NVidia GeForce MX/MX 440 video card. The video driver (which was originally an NVidia driver in Win ME) was replaced by a Microsoft driver, dated 2001. Graphics were slow with certain games & programs. But if I tried to upgrade, I'd get a blank screen on reboot, after Windows Starting Up screen.
After numerous upgrade tests, solution was to go to the http://support.gateway.com, type in the machine's s/n, & upgrade the BIOS & NVIDIA driver given there. Actually, note sure if the BIOS update was needed, but the NVIDIA driver that worked was version 15.20 (I know, old but it works) -- file 7511130.exe.
Also, check this out ->http://support.gateway.com/s/issues/1-103587706.shtml
Hope this helps.

John