|Set the boot order to boot from your optical drive first befor your hard drive.|
Run Memtest86 from a bootable CD to test your memory without needing to access your hard drive. this will do a couple of things for you. it will tell you if your apparent hard drive issue is actually a memory issue. It will tell you that most of your other hardware (other than your hard drive) IS working.
Run your hard drive manufacturer's hard drive utility (or just Seagate's Seatools) via a bootable CD to test your hard drive for problems. This will also be able to fix most minor problems and will tell you if your problem is too great or you have too many segment errors to be repairable.
Then try your repair.
If your memory is good and your hard drive is good or repaired, but the repair is not successful and your install CD will not run, then the install CD is probably bad since the other bootable CD's worked.
If you get errors on your memory, retry with one stick of memory at a time to evaluate which is bad and that it can run if you have only a good stick of memory in the system. No errors are acceptable with memory. Sometimes snapping the memory in and out a couple of times can improve the contact and make things work, but test to be sure. Replace bad memory as needed.
You have to be a little bit crazy to keep you from going insane.