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.

https://www.debian.org/ports/powerpc

Looks like even the latest Debian 7 is supported.

https://www.debian.org/releases/stable/powerpc/release-notes