At one time, Apple still had a supply of retail install discs for OS X 10.5 Leopard.
That, apparently, is no longer the case.
You need the Black background official retail install DVD discs.
You'll have better luck with finding this disc on Amazon.
You'll end up paying more than Apple's original $129 U.S. for these discs, maybe.
Tthe OS is over 5 years old, now.
Here's what I have found on Amazon.com.
Mac OS X 10.5 Leopard installation system requirements
Look on eBay or Google the installer part numbers to possibly find at an on-line store. Here's what to look for:
MB427Z/A Leopard 10.5.1 install DVD
MB576Z/A Leopard 10.5.4 install DVD
MB021Z/A Leopard 10.5.6 install DVD (single user)
MB022Z/A Leopard 10.5.6 install DVD (5-user family pack)
Installing Mac OS X 10.5 Leopard
Mac OS X 10.5 Leopard Installation and Setup Guide
After you install the base 10.5, download & install the 10.5.8 combo update at http://support.apple.com/downloads/Mac_OS_X_10_5_8_Combo_Update
The DVD should look like this
Caution - Leopard does not support classic mode. So, if you currently open OS 9 apps in classic mode, you won't be able to do this if you upgrade to Leopard.
Apple DOES have OSX 10.5 Leopard AND OSX 10.4 Tiger "Replacement" media available! I just ordered 2 copies yesterday. (March 12, 2013) You will need to call the number below and work your way through the automated phone service until you get a real-live customer service representative. Explain that you have a PowerPC G5 and need the 10.5 Leopard DVD media replacement. You will be asked for your computer's serial number. You can also opt for the 4-CD install set, but it's much higher. The price for the DVD with shipping is right at $17.
Apple support phone # 1800-767-2775
Are you sure these are not just replacement install discs that would've come with your Mac, initially?
Apple sells these at $17. The replacement install disc are discs that have the Mac original OS X version that shipped with that model Mac. These discs are Mac Model specific discs and do not work with just any Mac.
Almost all of the PowerMac G5 line shipped with some version of OS X 10.4 Tiger.
OS X 10.5 Leopard came later with the release of the new Intel Macs.
Replacement Mac machine/computer specific discs do not work across other Mac models.
No, these are "Replacement Media" DVD's. They are white in color and are still available through Apple. They aren't machine specific, as I have used mine on both the G4 eMacs as well as the G5's. Although the PowerMac G5's shipped with Tiger, most are more than capable of running Leopard. I was going to upload a photo of the exact disk but can't seem to get it to go.
All G5's can install up to OS X 10.5.8 Leopard.
I already know this.
If they asked for your Mac's serial number, these are Mac model specific system restore discs.
I Think it's just coincidence that they also work with your G5. Maybe these discs you purchased work with all PowerMacs?
I Would like to see if the purchased disc you got would work to install Tiger or Leopard on an Intel Mac.
I still cannot seem to upload any pictures. Here is a photo of the "replacement media" on photobucket.
That is the "Leopard" version. This disk installed fine on both the G4 eMac (1GHz, 1GB RAM) as well as all of my G5's.
It might just be a coincidence that they work on both. I do, however, have to use "xSlimmer" to remove all of the Intel coding from the Leopard install when using these disks, so maybe they would work for Intel models as well? I would absolutely love to find the original Grey DVD's for my G5's without paying a fortune for them.
Well, spread the word! I also ordered a couple of 10.4 Tiger disks as well. $17 dollars (USD) for the DVD is a pretty sweet deal. I was told that I could also get the CD-ROM set for systems without a DVD drive, but that they were $16 per CD. I should have asked about earlier versions availability...