Did you check out the temperature of your CPU, too hot or over-rated? PII is probably.....
Add more ram, try 256Mx4 b'cas it's the most economic.
Try oxygen or 3DLabs VX-1(around $1K) or GVX-1($$$)
I'm using them for my freelance and office work and performing excellent!
Don't trust any GeForce 4 stuff, they are quite fast in realtime rendering but rather unstable in showing the faces, and they don't really support OpenGL at all, so just use Oxygen or 3DLabs product! The rest are for game only!
Note that 'Realtime Rendering' is different from 'Rendering'
1st one is the time needed to show all the graphic on the screen while you are working, including the wireframe and faces, in this case, display card counts.
2nd one is the time to run a production class image(whether still pic or animation), in this case, CPU, RAM and display card counts.