Okay, here's the deal guys. Hopefully you can help me out a little bit. I have a macbook pro (2.2 ghz Dual Core) and I just recently upgraded my harddrive from a 100GB to 500GB harddrive. The harddrive is working. It's been erased and formated to mac extended format (extended). The OS X disk utility also recognizes that the Hard Drive is infact there. But here's the problem: when I start up the computer to install OS X, I get an error: 'Mac OS X cannot be installed on this computer: this software cannot be installed on this computer.' I'm using my roommates OS X disks since I left mine in Texas (I'm currently at college in LA. I have a legit copy of leopard at home). Is that the reason that the software is not installing? If so, do I have to get my leopard CDs from home shipped to me to get them to work? Or do I have to get my original factory CDs? Because honestly, I have no idea where my original computer factory CDs are that came with the computer are, but I know where my leopard CDs are since the computer originally came with Tiger. The harddrive by the way is a Samsung HM500LI which is sold on numerous mac upgrade sites as a working macbook drive. Thanks a ton.