I set my hard idsk size to 30,000 MB when I set up Parallels because I thiought I would be doing a significant amount of work on the Windows side. As it turns out, I am doing all of my work on the OSX side, so I don't need that large of a drive in Parallels. Can I make it smaller?
Don't know if it works the same on a Mac, but in the other 2 versions of Parallels the disk space is expanded in 2gb units as required. As long as you never used the 30gb, they have not been allocated so far, so if you don't use them you're o.k.. There are tools within Parallels that allow you to adjust the max size. You might ask this question on the Mac forum and get a more specific answer.