I agree with the above post on returning it. If you plan to edit your footage in iMovie (or any other video editing app) then you should have a MiniDV tape based camcorder.
The DVD-based camcorders are for people who will NEVER edit their footage on a computer. That is the whole point. You just shoot onto DVD and then pop that into your DVD player and watch. It's for soccer moms and grandparents.
The DVD-based camcorder is probably recording your video as MPEG2, which is a highly compressed DELILVERY format. MPEG2 was never meant to be an editing format. It was meant as a final delivery format. This is the same format that commerical DVDs use.
Even the "full qualilty" DV stored on MiniDV tapes is compressed, but not nearly as much as MPEG2. One hour of DV is about 13GB, one hour of MPEG2 is about 2GB. Generally speaking, of course.
I'm sure there are freeware applications that will allow you to rip your video off of the DVD and get it into iMovie. MacTheRipper, maybe? But, if you are going to edit your movies often--even just adding transistions and titles--this is going to add time to your workflow. That, combined with the fact that you'll be editing lower quality (more compressed) footage really means that you should move away from the DVD-based cam.
The good news is that you can also get a much better MiniDV cam for the same price because you won't be paying for the convience of DVD. Check out the Panasonic GS250, GS400 or the new GS300 and GS500. These are 3CCD cams which give awesome video quality. The mid-range Sonys and Canon Opturas are good too. Stay away from any other brands.
Good luck.