Question about Using Utilities with Snow Leopard Disc

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Quick question I'm trying to partition my hard drive to install windows and boot camp gives me an error that it can't move some files. So the problem is that some files are all mixed up and iDefrag didn't do anything for me. So I have read that I can run utilities of the Snow leopard disc and repair the disk and that should work, only problem is that when I insert it and open it up it gives me an error message saying that it can't do anything because it needs an older verision of leopard. So I thought I read that I need to boot from the disk. Now when I do that i get the gray screen at boot up with a folder and a question mark in it, and eventually boots into my desktop. Now when I boot from the disk is there something I should be pressing on the keyboard and holding the key to get into the utilities part of it to repair the disk??? Your help with this would be greatly appreciated.