Get the GF3 Ti200 anyday!!!
It has a lot more power than the GF4 card you mentioned there (don’t let the 4 fool you - the mx series roughly compares to the GF2 in terms of horsepower). The 3Ti200 also has one of those all important vertex shaders which are going to revolutionize CG so much in the months to come (especially with OpenGL 2 on the way).
I’ve got a 3Ti200 myself, and I never looked back. My Blender scenes run so smoothly now that it’s like having a completely new PC!!! One scene of mine, on wireframe, I was getting roughly 2 fps (frames per second) with my old card (a rubbish ATI card). With this new upgrade, I can dolly across this same scene in potato viewing mode (hold down middle mouse and drag to dolly) without any drops in frames at all. Astounding.
Not to mention the game playing potential of course. The UT2003 game demo runs on mine at 800x600 with everything on max, despite the fact my processor is 400MhZ (the game says it NEEDS a 733, recommended 1gHz).
So in short, get the GF3 Ti200 . Blender is just amazing with it, and you’ve got a lot of nice technology packed into this card which is really going to come in useful as the years go by (and with Blender 3).
Hope this helped.