Minimum graphics card specs for an HTPC

I'm thinking about using an old PC as a Tivo.

Nothing fancy, just a single tuner card so I can program the thing to save TV shows to a hard drive and play them back at standard cable or even broadcast quality later.

So my question is this....

whats the minimum useful graphics port for this limited application?

My old PC has a 1x/2x AGP port.

Should I even bother trying to use it this way (say with a 2x/4x video card) or should I find a mobo with a better graphics port before proceeding?

Thanks.