If you have a decent graphics card that can take an A/V input, your answer lies there. Otherwise you need a TV tuner card with A/V input, but this typically gives you crappy results unless it's a really decent tuner card.
The graphics card was top of the line in May 2005. Yes, I know that's a long time in terms of graphic cards. I know it doesn't have that shader thing-ma-jig version 3. But it may have an A/V input.
Otherwise, what's a good tuner card. How much should I be willing to fork out for it?