hi guys i bought a used 15" 2.2 ghz i7 with no install disks. i transplanted the hard drive from my 15" 2.8 core duo (a 500gb western digital running 10.6.7) and the i7 just wont accept the hard drive - the i7 just keeps getting stuck on the apple logo. are i7s different in some way that i am missing ?? any help appreciated.