Gaming needs fancy cards because some game specific effects are actually generated by the video card, not the processor. I don't think Bryce even uses active X yet. You probably can't buy a board old enough to slow Bryce down. 

What really kills in Bryce is when you have whopper scenes and shift the camera or objects and it takes 30 seconds to come back. That's memory, not video. Another meg is your best fix.

The GForce boards should do fine for even open GL renders in poser. The only thing I don't know about is Vue.