@diehardware :

For MorphOS and Linux, the G3 is fine (a little bit slow with Linux but not horribly slow !!).
For Mac OS X Tiger 10.4 for example, I have tested it on a Pegasos 2 G3 and some Pegasos 2 G4, there is a lot of speed difference but, as Magnetic says, it's usable on a G3.

If it can help you, great ;)
Faranheit