The cyrix may do better than you think.
The integer unit is reasonably fast, it's the floating point unit that is wimpy
A lot of the FPU burden of 3D games is that of the renderer, which is not relevant for a dedicated server. I'm not sure just how much FPU use is done by the dedicated server, but I'm pretty sure it's way less.
I remember someone I know running an 8 person Q2 server on a P60 or somthing similar - worked fine.
So why not load up Q3, start a DEDICATED server, run some bots, and join on a networked client machine.
It would actually do better with real people since the bot AI wouldnt have to run.
cot