I'm slightly confused

I planned to buy just a cheap little powerbook g4 and I was wondering 1)Does it run leopard? 2)Do I need to install os 9 on it? Thats about it. If someone could help me out that would be great.

1. It depends. The Leopard system requirements are on Apple's site for leopard (http://www.apple.com/macosx/) You will probably have to buy Leopard for it on your own, though.

2. Only if you wanted to run OS 9 software.

so I just have to install leopard on the powerbook if there is no os on the powerbook?

Yes, as long as the spec meets the link technologist gave, you only need Leopard, I seriously doubt if you will need any OS 9 apps

But make sure you max out the ram on your G4 to get the best out of Leopard

Guides on www.lowendmac.com and www.everymac.com will help you out

Any other problems, just come here