My current system is a celery 400mhz PC, which only works 90% of the time, and the power supply is dying.
The knockaround 'clunker' I have as a hobby computer is an Athlon 400, bodged together from leftover parts from here and there.
And it does a pretty fine job (all things considered).
I use Linux t - running UAE JIT on it and it has a pretty decent speed (even through X).
Hell I've run AmiWm running Galeon (browser), UAE, and Win98 (in VM ware) on 3 sliding screens for $h!ts and Giggles..
I'm thinking of putting Amithlon on there as well - though I have to look into it a bit more.
cheers.
Siggy