I bought a PowerMac G4 that was missing it's hard drive.I borrowed one a friend had that worked and the computer worked fine with it installed so I felt comfortable buying one for it.I got a used one from ebay so I probably can return it but would prefer to be able to use it. When I start it up with the new hard drive installed it opens up to a grey window with an alternating ? and icon of a file and it never changes.I have a dvd of Mac OS X Tiger 10.4.3 but this mac only had a cd drive and zip drive.I tried installing a Mac compatible dvd player but it still won't load the software.Can anyone help me with this?