I love my Blackmagic Intensity Pro because it has a breakout cable that provides I/O to a number of ancient and modern connections. It's very inexpensive, and performs well. Blackmagic has higher-end cards as well. Check Avid's compatibility page for details. My card is not officially approved, but since it uses the same driver as the approved cards, it works perfectly.
Read "Pro Tools Video Output Options Compendium":
DTS needs to make this a sticky:
http://duc.digidesign.com/showthread.php?t=260631
Best,
Nathaniel Reichman