Just because she is three doesn't mean that she doesn't need a more powerful computer. Kids software uses animation which requires a more powerful computer. I'd say some folks are pessimistic on the g5. It will take a little more work to get things squared away.
Be sure to get a black full install dvd. The grey one's are machine specific.
Mac OS X is rather relay-able. Could manually clean it out and define a new user id. This is always the risk of some inappropriate stuff being on the machine.
"You have to call Apple & likely ask for a Product Specialist to get it (Leopard), if they still have it... helps if you tell them you have a new iPhone (iPad) that needs it!"
BDAqua
Restore Tiger 10.4 & Leopard 10.5 DVDs are available from Apple by calling 1(800) 275-2273. Have your serial number ready. Have your credit card ready too. There may be a small fee.
Another number to try is 800-767-2775.
https://discussions.apple.com/thread/4720126?tstart=0 -- January 20,2013
https://discussions.apple.com/thread/5772721?answerId=24588313022#24588313022 -- January 22,2014
What are the part numbers for these disc?
http://support.apple.com/kb/HT2191
Requirements for Mac OS X v10.5
http://support.apple.com/kb/HT3759
Here is the browser to use on the web.
TenFourFox -- It's a port of the latest FireFox to run on older hardware and software.
"World's most advanced web browser. Finely tuned for the Power PC."
-- works for me on 10.4. Supports 10.5
http://www.floodgap.com/software/tenfourfox/
alternative download site:
http://www.macupdate.com/app/mac/37761/tenfourfox