Upgrade to 10.5.8 from 10.4.11

you need to buy 10.5 upgrade discs, look on ebay or craigslist, they wont be very cheap though , make sure you get proper disc, dont buy them if there grey disc, as they are machine specific

You will need a Leopard install disc. They were originally $129, but I'm sure you can find them cheaper now...

Sorry, but that's not good info. Hope you come back...

Call Apple to order a Leopard retail disc. Last month, I saw a post that said "I got it for $80."

If you order from eBay seller, you might get a machine-specific disc (or set) that will not install on your Mac, unless you have a system for winning the lottery.

People selling their old disc sets are trying to turn them into cash, and are charging outlandish prices in some cases. Stay away from gray discs. You want the black one with a big X on it.

To clone a hardd drive use carbon copy cloner - http://www.bombich.com/ or superduper.

My recommendation to you is the following:

1. purchase an external hard drive with a firewire connection.
2. backup your drive to the external drive using super duper (I like super duper more than carbon copy cloner, but both are good).
3. Change your settings so you boot from the external hard drive (this is one of the cool things about OS X, that the boot drive can be internal or external).
4. Upgrade the external drive OS from 10.4 to 10.5 using whatever option you like.
5. Make sure you are happy with the results.
6. Change your boot drive to your internal drive and perform the upgrade (alternatively you could just use super duper to copy the contents of the external drive to the internal drive).

Of course if this is a new machine and you haven't started populating it yet with your user data, then I would simply go for a fresh install of 10.5 without going through the hassle of testing the upgrade out on an external hard drive first.