My parents need their computer really soon so do you think its the hard drive? I'm about to buy one from newegg.

If you've tried;

If you can't find anything on the DELL forums, the only other things I can think of is;

If not already so, place the CDROM drive (as the slave) on the Primary IDE channel along with the primary boot hard disk. This will slow down the copy process which may help.

Then in my opinion, it's the hard disk. You've tried everything else;

New CDROM
Memory has been checked
Cable is good
Using OEM media