I have a Mac Pro running FCS2. I would like to take a video feed to a (CRT) monitor which has various composite inputs (scart, BNC etc) so that I can check color and picture quality. What would I be better doing:

1) Getting a USB capture card and routing it via that, or
2) Getting a PCI card that could do the same job?

Looking around there seems to be a huge difference in the price of PCI cards.
Any reccomendations on makes or models of cards for either options?