Running XP:Pro off Jump Drive?

Howdy, everyone.

This is an idea I've had in my head for some time, and would like to test, even though I'm nearly certain it'll just end in failure.

What I'd like to do is install a full copy of XP onto a Jump Drive. The theory being that I can install all my applications, games, et cetera onto the hard disks, and instruct my computer to boot from USB.

This meaning that if I walk away, I can simply power down, remove the jump drive, and my computer is little more than a paperweight until the 'key' is plugged back in.

Now, the problem comes with speed. Modern era hard drives near an average of 100MB/s transfer (a bit faster by now, I'd imagine), whereas the fastest Jump Drive I can find is ~60MB/s read, and half that for write speeds.

My question is this: I know that the OS loading would take forever, but afterwards, after the OS has loaded all its components into memory, would the speed difference still be that noticable?

Also, I know about USB proximity keys, and all that jazz. I also know about Linux, and its hundred derivitives. I'm not interested at the moment.

And incase anyone is wondering what spawned this, at college, one of my professors said that he can shortly see a day where internet cafes, et cetera, will be comprised only of 'clean' boxes, and you plug in a thumbdrive, your OS loads, and you're off. When you're done, unplug, and the "computer" is back to a clean slate. I don't know why, but that gave me this idea. Heh.

Any help would be <3.