I'm completely confused now, what's going on.
I just want to get this straight, you have a Motherboard w/ onboard nvidia video card. But you're not using the nvidia card, you're using an ATI Card?
If so follow the directions below:
Ok uninstall the ATI driver, reinstall the Nvidia drivers that came with the mobo.
Reason why smartgart is not getting installed is that there is traces of the old nvidia driver.
Now get nvidia detonator: Nvidia Detonator 4 XP WinXP/2000 Drivers @
http://www.voodoofiles.com/4673 run this program to fully remove the nvidia driver.
Now when Xp starts nagging you that it found new hardware close that window, and pop in your cd that includes your ATI drivers and choose full installation. Better yet, d/l and install the newest catalyst drivers, I think it's 4.4.
You should now have smartgart, since it comes installed with the ATI driver.
Right click on the desktop--->select properties--->click on the Settings tab--->Click the Advanced button--->Select Smartgart tab--->you should see a slider that allows you to adjust it to either 4x or 8x.
Let me know if this solves your problem.