The thing with flash drives is that the faster they are the more expensive they get, this relationship seems to be exponential. If you find something fast enough it will cost you an arm and a leg. Are you really willing to put down that much just to run windows under linux. Try these:http://www.corsairmemory.com/corsair/flash_memory.html http://www.flash-memory-store.com/4gb-apacer-handy-steno-ht203-133x.html
And then look for them on newegg.
But somehow i think that the hdd will still be faster, even through all the noise, you are kind of trying to push a square peg through a round hole. USB is not suited to such things, even usb 2 and flash memory is not good for much else but pure and simple storage.