[Jonathan]

Was curious to see if I could load OS 10.5 on my older IMAC, currently running 10.4.11. I used the system discs that came with my wife's newer IMAC computer purchased new last summer.

 I put in the system disc and clicked on the install icon. The computer restarted and got to the install screen, where I selected "English" as my preferred language. But that's as far as I could go before getting an message saying OS X cannot be installed on this computer. I rebooted from my hard disc and all is as it was. I'm curious as to what happened.  I appreciate your input.

Jon

[orthobiz]

Check your processor speed. I believe minimum is 867 MHz or 10.5 won't run. Check under the upper left apple in "About This Mac."

Paul

[jaywills]

IIRC, it's difficult to run Leopard on a G4 and impossible to run it on a G3.  Good luck.  Cordially,

[Jonathan]

Thanks to those who responded. I have an Intel IMAC 20" desktop, so it's not a problem with the computer.

After doing more research, I believe the answer is that (afaik) the system discs are proprietary and will only work with the computer they came with (my wife's). Too bad--I hate to spend $120 on a new version of Leopard.

[andrewbee]

The 20" iMac is fine for Leopard. The system restore disks that come with computers are not so much proprietary as they are O.S. dependant. IOW certain macs require a certain minimum OS version to run. The way for you is to purchase the Leopard upgrade which does not make much sense now as Snow Leopard is just around the corner. Why do you want to upgrade to Leopard? Besides Time Machine and a few other imo minor differences its not all that much different than Tiger.

[oneinthepipe]

Why do you want to upgrade to Leopard? Besides Time Machine and a few other imo minor differences its not all that much different than Tiger.

I am not the OP, but the restore disc can be saved to a disc image and modified to install on most Macs.  There are instructions on the web.

For me, the most significant reason to upgrade to 10.5 is Bootcamp ver. 3, since I often run Windows on my computers.

[Jonathan]

Why do you want to upgrade to Leopard?

Nothing particularly wrong with Tiger; however, I've seen a few interesting freeware or inexpensive apps that seem to run only on 10.5. I've read that the Snow Leopard update is only going to run $29, but I assume that's for folks who already have Leopard.