iMac 600mhz OK for Server

Trying to do research and can't seem to find enough info, if this is a good route, being I can pick one up for $70.00.
Any input appreciated.
Is it a G3 or G4. Either would work, but the G4 will give you better performance running OS X software.
It is a G3. I did not know what I would be gaining by having the Mini, other than footprint.