I have Firefox running on my 300Mhz RiscPC. It is slow
and very unstable,but very complete..

The real advatage of the RISC OS port is that is uses
a library that translates X windows calls to RISC OS
wimp calls. It is created with the GCCSDK wich runs on x86
linux and makes it possible to port unix programs
without modifications to RISC OS.