I am running with a Geforce 2 MX with TV out (64 megs) and so far no problems with the video. However I am new to this and have only used GBPVR for viewing live TV.
More regarding the Geforce2 that I have... During fast motion I have noticed that there are some "jaggies" around the edges of the moving image and am contributing it to the card. While watching slower motion or stills the card does not have the "jaggies". I read that this card was the minimum requirement for my TV card. Possibly the Geforce3 would be better.