To resize your boot camp drive partition on the Mac you have to wipe out all of the data on the partition. Of course, you can back up the data on the partition and restore it after you are done. But jeez, what a pain.

A product called CampTune (http://www.paragon-software.com/home/camptune/) is aiming to fix this problem. Using there software, which is still in beta so it's a little scary, they can resize the boot camp partition without affecting the data on the partition. It's also easy to use. You just insert the DVD into your drive, reboot and follow the prompts.