An interesting challenge1  so, I thought, how about running the same matching work on two matching machines.  I chose P3 because it has the easiest benchmark to work with.
In this corner: an iMac G3, 450 MHz, 256 Mb of RAM, OS 9.2
and in this corner: an NEC A1000, 450 MHz, 256 Mb of RAM, OS Win 98
In essence, both machines are identical (they even look the same, the NEC is single unit machine, built like an iMac), neither are connected to the internet.
Okay, first off, start the machines..... the iMac boots faster, go to make coffee while the PC is still spooling up.
Once the machines have warmed up, Open P3 (Freeware versions).  The PC opens the application faster.
Select Raptor from Figures, add the Groundplane, single source lighting overhead. Pose in killer stance.
Press Render......
the iMac rendered faster but not by much.
So, there you go, a true benchmark test .