Can I upgrade from 10.2.8 (GS) Power PC G5

Depending on what else you may be doing with older Mac systems and their applications

you may look into Tiger 10.4 (retail DVD install) while likely harder to get than Leopard 10.5.

Even older pre-X applications could be run under "Classic" mode in Tiger 10.4(.11) that may

not be available in Leopard 10.5(.8). And Tiger was more refined than Leopard. I've vintage

Macs that run both. ~ You can get & use TenFourFox browser in Tiger and Leopard.

TenFourFox (browser for Tiger & Leopard PPC)

http://www.floodgap.com/software/tenfourfox/

Also iTunes player application is still available from Apple downloads; for music & internet radio.

iTunes for Tiger 10.4.11 & Leopard 10.5.8

The iTunes player offers surprising number of residual free stations to listen, in Tiger & Leopard.

(Also iTunes works in early model Intel-based Mac that may have gotten lost due to failed backup.)

Another caveat: do not get a download OS version. Apple never released 10.5 and 10.5 for download--it will be pirated and may well contain malware. Also burned disks have a very poor track record of working for system upgrades.

A good source of proper old OS disks are Mac User Groups: User Groups - Apple

If you send a "looking for" e-mail to the group's posted address, you might find what you need.

You should be able to update to 10.5.8 Leopard. However, you will need to buy a retail install DVD to do so.

Apple no longer sells Leopard, so you will have to find one on ebay or the like.

Do note that they must be the black retail install disks. As grey update disks will not work as they are keyed to specific Macs.

The Low End Mac (LEM) Swap list is another possible source of OS install discs.