I have an old Powerbook G4 [ Power PC G4 (1.1), CPU Speed: 1.5GHz, 512 MB DDR SDRAM] with a Mac OS 10.3.9. I am having problems running internet browsers etc. I am told that with the PowerPC processor, I need to upgrade the Mac OS to at least a Mac OS 10.4.4. Where can I get a software upgrade and how. I will appreciate some tips and some help on this.