Am I Missing Something?

O.K., I capture DV at a rate of about 100mb per minute, does that
really mean when I record it onto CDR I can only get about 7 minutes
of footage? Or does it get compressed before going to disk? I've tried
several different settings, but the only one that doesn't chop about
25% of my screen away is DV/MPEG2. I've also tried MS MovieMaker and
Ulead VideoStudio6. Any suggestions for getting at least 20 mins of
full screen video on a CDR? I would appreciate any help. Thanks.