Ugh, why don't you make another partition?
I partition my hard drive so that my data and projects and stuff don't need to be transferred when I do things like reinstall my OS. I find it's almost universally better to keep my OS hard drive small and keep the rest of stuff elsewhere.
If you really want to have the space on your C drive, you can create a partition there, and then create an empty folder on C, then mount the drive in the emtpy NTFS folder. So for example, you could create c:\Space, and mount the partition there. I do that with my music. That way I can have music in my c:\users\Rob\Roaming\Music\ folder but it's really on something like i:\. That way whenever I format I don't need to back up those files.
