Hi - I've done quite a bit of research on upgrading my iMac from os x 10.4.11 to os x 10.5.6, and still cannot figure out what I am supposed to do to install 10.5.6. I get the infamous "cannot install software on this computer" when I try to boot the DVD. This iMac OS X Install DVD came with another iMac I bought for my family. I want to update my 20" iMac with this software - I thought you could share amongst a family of computers. Is it that you can only install that software once? I will buy OS 10.5 Leopard no problem just want to be sure I will not waste money if my computer doesn't support Leopard. Basically I'd like to know if I bought Leopard (assuming I can't use my families disks) will it work on my computer? Here are my computers specs: Model Name: iMac Model Identifier: iMac5,1 Processor Name: Intel Core 2 Duo Processor Speed: 2.16 GHz Number Of Processors: 1 Total Number Of Cores: 2 L2 Cache (per processor): 4 MB Memory: 3 GB Bus Speed: 667 MHz I've read that you need 887 MHz, but is the Bus speed the same thing as processor speed? I'm a Mac novice trying to make it work. Any advice is greatly appreciated! Also, I have the partition set up as GUID, and if necessary I have a separate hard drive. Thanks!