Bootcamp, finder, software update issues

Hey all,
about four or five months ago I got a new computer - a 21.5 inch 3.06GHz Intel Core 2 Duo iMac (currently running 10.6.2).

All was going well until I decided to install bootcamp. I tried to partition the hard drive, but it gave me an error saying it can't move some files, and that I need to format the hard drive, which I don't really want to do. I google'd solutions, finding it was fairly common, and tried every solution I read. Defragging didn't help me either.

Looking in disk utility, I clicked 'verify disk' as I saw to do elsewhere, and it tells me 'This disk needs to be repaired. Start up your computer with another disk (such as your Mac OS X installation disc), and then use Disk Utility to repair this disk.' I then tried to boot the OS X disk to use disk utility, but it refused to boot it. The only solution I could find for THIS problem was to reset the PRAMs by holding command, option, P and R on startup, which I did. However it didn't appear to do anything, so I gave up on boot camp.

Now trying to use the computer, it gives me errors in finder when trying to copy or expand, claiming the 'the file ____ already exists in this location.'

Oh yeah, I tried software updating three or four times too. First few times it failed downloading, next few it downloaded it but then was unable to instal it.

Any solutions out there? Or do I have to format the computer or what?
Thanks very much.