You definitely want to use firewire if it's an option, grock.

Technically, a capture card converts a video signal from one form (say analog video) to one the computer can understand (sometimes an MJPEG, sometimes an AVI, sometimes a MPEG). And, even with the best capture cards out there, in any conversion there is loss.

With firewire coming from a DV camcorder, though, there is no conversion at all. In fact, you're not so much capturing as you are simply transferring the DV-AVI files as is from your camcorder. Not only is there no loss in quality whatsoever in this process but, since the computer and camcorder are speaking the same language, all things remain in the digital world, the very world in which your video editing software lives.

All any analog capture card can do is simulate that.