Okay so I recently lost my hard drive. I got a new one on eBay and I believe it has a newer version of Mac OS. I do have the OS 10.4 (tiger) (whoch should work for my laptop) but when I turn on my computer I get the apple logo and the spinnig wheel for hours. If I put the disk in there and hold c I get the same thing. If I hold option with the disk in there it shows me the hard drive disk looking thing and once I click it it does thR apple logo spinning wheel. I believe if I erase the hard drive and reinstall my Mac OS 10.4 that it will work fine. I don't need the newest OS just a laptop that works. I have replaced the hard drive before with no problems but my idiot son put a magnet on my last one wiping it out so I was forced to buy a new one only to be stuck with this Problem.