So I was able to partition a Macbook Pro 2010 (Snow Leopard) using Boot Camp in order to install Windows 7. I just want to point out this possible solution when you get this error when trying to create a partition:

Your Disk Cannot Be Partitioned Because Some Files Cannot Be Moved

Back up the disk and use Disk Utility to format the disk as a single Mac OS Extended (Journaled) volume. Restore your information to the disk and try using Boot Camp Assistant again.

Note that I said this is a possible solution. That means that this may not work for you. Most of the solutions I found on the Internet point to using defrag tools like iDefrag. I didn’t want to go that way cause I really don’t have the money to buy those tools.

Here’s what I did to fix this error:

1. Clean up the hard drive. Move large files to an external backup disk. There are tools like OmniDiskSweeper to that can help in finding large files.
2. Reboot and boot up using your Mac OS X Install DVD. (Press C when after the startup sound to boot using the DVD)
3. Choose Utilities > Disk Utility in the menu and Repair the hard drive.
4. Restart and try partitioning using Boot Camp again.

I’m not ultimately sure if Step 1 is really required but I don’t have time to test it again.