[Ti] New to the Group

[ebachman at roadrunner.com]

This is my first Mac since my first computer back in 1994 when 16mb of RAM was way cool. I just traded my iPod Video for a TiBook G4/400, bumped it to 1gb RAM and have a 120gb HDD on the way. I'd like to upgrade the OS (currently I'm running 10.3.9) to allow me to load NeoOffice. Would it be wise to upgrade to 10.4 or 5?
Other than that I was toying with the idea of replacing the processor but I've heard that can be challenging to say the least.
Thanks for your advice...e