I need to upgrade my PowerBook G4. Currently running OS 10.3.9 , 1 GHz w/ 512 mb memory. I plan to boost memory to 1.24 gb, then want to upgrade OS. Can I go directly to 10.5, and if yes, what's the best way to do it. Or would I be better off just upgrading to 10.4. Please keep answers as simple as possible - I'm not the most computer savvy person.