"Files cannot be moved"-error Boot Camp

Hi!

I have a bit of a problem.
Yesterday when I wanted to boot Vista Ultimate 32-Bits on my 20" iMac (late 2006 model) it only gave me BSODs at startup and then rebooted my computer automatically. I tought: OK, let's just erase Windows. So I fired up Boot Camp-assistent and deleted the Windows partition.

Today, I wanted to reinstall Windows Vista again, but when I tried to partition my drive with bootcamp, it gave me the error saying that my harddrive could not be partitioned because some files can't be moved. It says I'll have to format my hardrive to 1 partition using the Drive Utility. But I'm very afraid I do something wrong and that Mac OS can't boot anymore. I also don't have a drive to store a back-up of all my files on.

My question is: Can I just ignore this screen and if I do, will I be able to start Mac OS X normally?
I DO NOT want to install Windows after this anymore, guess I will buy a PC for games in a while or go to my friend's house to play Crysis and such.

Grtz. Yvo25

*EDIT* Just did a disk check using Disk Utility, it says with green letters: The disk is OK.