Realtime MPEG2, very good suggestion... Just be sure it's hardware and not software! Many cards CLAIM they are realtime, but in fact, they use only software encoders. This results in lower quality and usally dropped frames.
As for capture or TV Tuner, they are the same thing, but the TV Tuner, obviously, has a tuner in it. If you plan to capture cable TV, get the tuner. Othewise, you'll have to use RCA or Svideo to send video into the card...