Paperlantern pretty much described the bulk and I would definitely follow up on that, and also for the rest of us which are very forgetful, there are negligible things that I'll make a checklist for just in case
Firstly, I would go into BIOS and do a little check there, I know the newer motherboards have AUTODETECT but sometimes you never know.
Also, I would make sure the IDE cables are connected correctly, (Master is outer and Slave is inner) and then I'd just check to see that the jumper is set to Cable Select.
Then I would go to Paperlantern's suggestions.
Lastly, I would download Seatools do a full diagnostic test, and see if the hard drive is really the problem.