For the general edification of anyone interested in what hardware makes an MMO go, CCP posted up an inside look at Tranquility today:
http://www.eveonline.com/devblog.asp?a=blog&bid=769
This is what you need to have 50,000+ players all in the same game-world.
And here I thought my 34 PE1950s (2x quad core @ 16gigs) was impressive.