Sort of hijacking this thread...
My brother has a dual Celeron 400's mobo, and he's running XP (God, no!). He's found that XP only starts to use the 2nd CPU when the 1st one is overloaded - such as ripping CDs and converting to MP3 at the same time, so for running games and stuff, it'll still run as a 400MHz machine. How does Linux use the 2nd CPU?
(I am thinking of buying it from him