Several questions come to mind.

1. Did you prep the drive--partition and format before trying to load the software.

2. What operating system are you trying to install--if your processor is at least 933 you can use 10.5 if your memory is maxed but I would recommend staying with 10.4.

I am including a link to an Apple guide to installing software. This guide is for reinstalling but has useful info that may help you. Good luck. Ralph

http://support.apple.com/kb/HT3200