Tiger is no longer available from Apple. You may look for a retail installer package on eBay, Amazon.com, CraigsList, or via Google search. You can install Leopard which you can purchase from Apple:
Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.
To contact product and tech support visit online support site.
There is no copy of OS X available for download except Lion which cannot run on your computer model.
Call them & see if they still have Leopard/10.5 available, they did about a month or so ago, but supplies were short.
* Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor
minimum system requirements
* 512MB of memory (I say 1.5GB for PPC at least, 2-3GB minimum for IntelMacs)
* DVD drive for installation
* 9GB of available disk space (I say 30GB at least)
You have to call Apple & likely ask for a Product Specialist to get it, if they still have it! Helps to tell them you have an iPad/iPhone & you can't run 10.6.
*Mac OS X 10.5 Leopard installation system requirements*
Leopard is no longer available at the Apple Store *but may be available by calling Apple Phone Sales @ 1-800-MY-APPLE (1-800-692-7753)*.
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 Leopard installer is on a DVD. You need to increase the amount of free space on your hard drive before installing Leopard. Your HD will be almost full if you install Leopard & you risk disk corruption & slow operation.
If the software comes on a DVD, and my system won't read a DVD, then I need a version of the software I can download and install. I also have Mac Mini running OS 10.6.8 on the same network, so a network installation can be done, but I will need step-by-step instructions for doing this.
You can use system profiler to check whether you can read DVD's.
the blue Apple icon > About this Mac > More info…
goto the hardware section. Scroll down and click on disk burning
There is a way of using Target Disk mode to read a dvd from you other computer.