Carry your computer on a USB drive?

i just ran across an article called Travel Without the Laptop, Carry You Computer on a USB Drive. The premise is you can install enough software to make any available computer your own by simply plugging in the USB drive. Notable is MojoPac, which looks like a leech that uses a PC's OS to do the gruntwork, but what i really liked was the Portable Apps section. i already use Firefox, Thunderbird, Filezilla, and GIMP. Pidgin looks cool so far.

Change of subject- i recently developed Mac-envy. Fortunately i was cured upon reviewing prices at store.apple.com. That lead me thinking about alternatives. i'm just over with Microsoft. Apple of course is genious (mostly about making profits, really) and i'd enjoy one but i'm stingy. How feasible would an open-source laptop be as an alternative? Like one that runs Ubuntu? Anyone had experience with a Linux GUI?