Over the last few years I have been blown away by Ubuntu and it's progression, I am happy to say I have not booted into my windows os's in over 2 years, but I get plenty of practice fixing Windows for clients.
Ubutuntu 10.04 has some real ground breaking features this go around, with new out-of-box support for most wireless cards, Nvidia graphics cards, and all the mobile broadband cards I could throw at it, including sprint, cricket, also my palm-pre as a usb network device.