I'm not sure what the possibilities of your particular system are, but GNU/Linux systems, i my opinion, do a a fantastic job of letting all kinds of systems use the latest and greatest browsers. I remember running Debian on a tangerine clamshell iBook a couple years ago.
I do this. I have stacks of Apple PowerPC machines (lamstand imac, 5 mac minis, G5 Mac desktop) and honestly, it's not worth wasting time on. Linux on PowerPC is really a second-tier architecture. 3D acceleration is subpar and there's no Flash, so you're really limited for a browsing experience.