Windows 98 is pretty horrible by today's standards though - to be honest XP will run nicely on a 500 MHz as long as you have a reasonable amount of Ram or do a little tweaking, I think it would be a waste to only run 98 on one. As for a G3, why would you run only OS 9 on one? Stick some memory in there and OS X flies on them! Macs seem to remain modern and useful for longer than PCs - while a 500 MHz PC is from the G4 era, G3s from 1998 are still very very useable (with Tiger).