eric2006
iMovie Professional
I have the same problem you do with Bootcamp. I don't think it has anything to do with disk space. The "Can't Move" error is because the Boot Camp assistant has to create a new partition on your drive, and where it wants to write partition data to has data in it. So, BootCamp then tries to move the data (file) to another sector/cluster on the drive, but can't for some reason. My guess is that there is a process running that has a lock on a file that the Boot Camp assistant wants to move. Make sure that you have absolutely no apps running, and that your menubar has no apps running in it. (Like MenuMeters, or Gmail Notifier, etc...)
You might want to start in safe mode to make sure you're only running the basics:
http://docs.info.apple.com/article.html?artnum=107393