I had a similar problem with my TRV-520. The first thing is that you're gonna want to use IEEE 1394, AKA-Firewire. It supports a faster transfer rate than USB. With that you will get better quality transfers. When I first got the camera I didn't have a firewire card at the time so I go and pick up this cheesy $20 deal that ended up not working. I ended up buying Pinnacle's Studio DV software that came with another card. After installing that and plugging everything together it was then seeing my camera. Another thing that you have to consider is the transfer rate over to the hard drive and the amount of space. If the drive that you're going to capture to cannot keep a sustained speed of 4mb a second then you're gonna have to look into getting one that can do the faster transfer rate. The second part of this is the size. In digital format video takes 3.6mb of space for second of video. With the Pinnacle software they do have "SmartCapture" that can be used. Using this will capture the video at Preview quality which uses less disk space.
So if you don't have a firewire card I suggest you looking into one. If you end up picking one up then you'll need the firewire cable for the camera which you can pick up here: