Yeah, with a digital handycam, you'll probably need a FireWire card (also known as IEEE1394 or i-Link) which cost $130+ I think. For transferring good quality video, USB is just too slow really - it only does 11 megabit per second I think. I guess for smaller clips (and with a bit of patience) it might be okay.
You might also want to think about what editing software you'll be using on your PC to retrieve the video from the camera and then how you're going to save it. MPEG(2) is okay, but still quite large files. The world of video codecs is a bit hairy, unfortunately.
But yeah, a lot of what you need in terms of hardware specs depends on how much video you're wanting to edit, and what kind of quality.
Check the different cameras for included software. I know Sony includes a CD with some simple software with a lot of their range - probably makes things quite easy to get going.