poor video performance with soldier of fortune and ghost recon

I have an Intel Celeron 700 mhz, Windows ME, and a GEFORCE 4 MX 420. When I get to high action points in these games I experience a major disruption in video performance. I took the system into Best Buy and they said I should update the latest OPENGL drivers, but as far as I can tell I have them… They said that there are specific OPENGL drivers for each game??? Please let me know your opinion… thanks!