The other day, I found myself holding the N key in guidgen, trying to exhaust all 340282366920938463463374607431768211456 GUIDs. I didn’t count, but I think I got to around a 1000 GUIDs so far… I was just that bored. I guess I was hoping for a cool “OUT OF GUIDS” BSOD or something.
kichik's blog 
LOL
Oh, stop doing this, Kichik!
Soon you’ll steal all the world guids, and poor microsoft will need to change their uid system somehow.
You shouldn’t be such indiscreet, even if you are bored.
=) 😛
I tried to do this some time ago. Well, I considered trying to do it, then did my sums and decided it wasn’t worth the bother: http://rikkus.info/running-the-world-out-of-guids.html