
Yup, for a 800mhz CPU and bearing in mind current prices and games it is well worth going for a GF3 (TI200 great price) or Rad8500 (LE well priced too). If you are thinking of a CPU upgrade within the next 6 months then 128MB and even GF4TI4200 are definitely worth considering. 4200-64MB $130, 4200-128MB $150 while Rad8500LE/GF3TI200 $90ish. If Rad8500LE and GF3 cards are evenly priced the Rad is the better choice, I can go in to the why's & how's if you wish, GF3 are close esp if you want top AA and high quality Aniso.

This link is great to see what diff cards (and diff CPUs) will get you:
AnAndTech CPU Scaling Article.