What you are looking for in a video card is "video-in" features.
As for a nVidia type card:
Asus makes a few Geforce FX cards with video-in capabilities such as:
For the complete index of the cards and a list of less pricey ones you can take a look at their complete line of video cards. Just look for "video-in" in the specifications
Also, have you take a look at the ATI All-In-Wonder series of cards?
Are there any video cards [nvidia chipset] that have SVideo input port to allow capturing video from a VCR via SVideo???