ATI All-in-Wonder cards are great for this, though it might be a bit overkill for your needs. If not that card, then consider the ATI 64MB DDR Vivo. I have that card and the in/out features work great! ATI uses a better capture component that Nvidia's GeForce2 and GeForce4 line.
Keep in mind that the resolution on your TV is not as good when compared to your monitor. It's not uncommon to see fuzzy text or blurred images. You have to play with the output settings to minimize the loss of quality.
Also, if you plan on playing newer games, you may want to make the extra investment for a Radeon 8500 or 9700 All-in-Wonder.
~cdogg
"The secret to creativity is knowing how to hide your sources."
- A. Einstein