snow leopard

The only option available is to buy a Mac OS X 10.5 DVD from a source such as Amazon or eBay. A G4 or G5 Mac can't be upgraded past 10.5.8.

(84356)

Below are some sources for MacOS X 10.5. Be sure to get the Retail Install Disk which looks like this;or original disks only for a PowerBook that is identical to yours.

Some have rather ludicrous prices so eBay is likely your best bet.

http://www.welovemacs.com/osx1opso1.html

http://hardcoremac.stores.yahoo.net/

http://www.buycheapr.com/us/result.jsp?ga=us14&q=leopard+10.5+os+x

http://oldermac.hardsdisk.net/oldmac.html#hard

http://www.ebay.com/sch/i.html?_mdo=Computers-Networking&_from=R40&_sacat=0&_dmd =1&_armrs=1&_pcats=4599%2C58058&_nkw=Mac+os+x+10.5&_lncat=0&_arm=1&_armm=94&_ruu =http%3A%2F%2Fwww.ebay.com%2Fsch%2FVintage-Computers-Mainframes-%2F162075%2Fi.ht ml%3F_mdo%3DComputers-Networking%26_from%3DR40%26_dmd%3D1%26_armrs%3D1%26_pcats% 3D4599%252C58058%26_nkw%3DMac%2Bos%2Bx%2B10.5%26_arr%3D1&_armi=Vintage+Computers +%26+Mainframes

Not all models of G4 can upgrade to Leopard.

Mac OS X 10.5 Leopard installation system requirements

http://support.apple.com/kb/TA24950

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

http://support.apple.com/kb/HT1544

Mac OS X 10.5 Leopard Installation and Setup Guide

http://manuals.info.apple.com/en/leopard_install-setup.pdf

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

 Cheers, Tom 😉

Note, after installing 10.5 or later, you will no longer be able to access Classic. Some Powerbooks offer the option to dual boot 10.5 and 9, if you have the right setup.