New OS for powerbookG4

I am in need of a new operating system, and do not know which one I can use for my computer because it is older.

As of now, I have MAC OS X version 10.2.8
It is a 512mb and 1GHz PowerbookG4

I am looking for the newest operating system that will work with my computer, because I cannot update my itunes, firefox, iphoto ect.

same laptop


throw in another 512mb.... (if your in the states its cheap !!) and upgrade to 10.4.10

Mine runs perfect. they are great machines. dont get sucked into this mad game of " You got to have a new mac " !! you dont... i know music guys that do all their stuff on a G4 and have never worried...

how do i add another 512mb?
if i upgrade it to 10.4.10 will i have all of the new features?

and where can i buy it?