resurrecting old G5 need to ugrad OS 10.3

Hello all you who know more than me.
I dug out an old imac G5 desktop running 10.3.9, which won't run modern brouwsers. How do I upgrade to more current OS and what is the most current OS I can upgrade to?

1.8 GHz
1G RAM
Power PC G5 (3.0) CPU
600 MHz Buss
Boot Rom Version: 5.2.2f4

Thank you so much,
Darryl

You can upgrade to OS X 10.5 Leopard. Will cost you about $100 on Ebay.

Like MacDude said, 10.5.8. Ebay is probably your best bet.

Also with Leopard 10.5 I would put in another Gig of RAM for 2GB. 1GB will work but it will be a lot smoother with 2.

But be sure you are buying a "retail" copy of Leopard. It is a black disc with a big X on it. Don't buy a grey disc. Those are machine specific and would have to be for your exact model to work.