Have a funny feeling that your G/Card might not be upto the challenge.
I'm assuming its onboard.
It is possible to install the Win98 OS and XP in tandum. However, can be a pain in the arse setting it up, and switching between OS's just to play a game. Therefore, suggestions, try and get a slightly better G/Card, AGP or PCI, about 32mb, shouldn't be much. That could help. Failing that, try lower screenres, reduce framerate to about 14, and try without the N0-CD patch. That would mean a reinstall, unless files were backed up.
Hope those suggestions help.