Tape time is limited to an hour at high quality (not HD), but you can always buy more tape, unlike hard drive cameras. Hard drive cameras have a finite recording time. Once you've filled it up, you might as well pack it away until you can get to your computer. If you go with a hard drive model, check how much time you can record in high quality mode.
Cameras that record to digital cards have the benefits of tape, but not the possible mechanical tape problems. For instance, my Canon miniDV camera eats tapes now, making it completely useless except as a web cam or for recording direct over the firewire cable. In other words I don't use it now.
Getting the video off of tape to your camera is done in real time, meaning for every hour of video you have, requires an hour of your time to get it into you computer for editing. Although iMovie may convert the video from a digital medium camera, it usually is an effective drag & drop type action because the computer sees the camera as drive. This gives the ability of faster than real time import.
People have argued that miniDV produces better picture quality for the same size picture. This seems to be due, at least in part, because the manufactures are over compressing in the codec on the non-miniDV cameras. I think this may have been getting better, but thought I should mention it. Search Google for reviews of your camera choices.
I figure you'll be using iMovie for now, so also watch out that the camera works with your version of iMovie directly. Some don't or require that you first convert the video through a third party application.
Consumer HD cameras have been coming down in price. For your money you should be able to get at least a 720p HD camera. If ordering from an online store, then as usual find opinions on the store. Some places have prices to good to be true. You may get the camera advertised, but not the usual parts.
