I'm building a laptop for work, and it has a completely fresh install of XP on a brand new SSD on it. It's a plain jane Dell D830, 4GB Ram, 32-bit XP with a C2D.
Granted, fresh XP always runs great, but fucking hell is the SSD awesome. Completely cold power off to at the desktop in about 10 seconds, if that.
I really need to snag one for my Macbook. OSX boots fast as hell anyway, I can't imagine how it would be on solid state.
I put a Kingston 64gb SSD into the C2D laptop I used to have and it did most things faster than my desktop. Booting Windows 7? Never more than 15s. Ubuntu? Same. That SSD is now in my desktop as my boot and main apps drive, it's fantastic... And it's not even one of the super fast drives!