So I have upgraded my macbooks hd to the 250gig version. Now i would like to make my old hd an external any cases you reccomend? I would like it to be powered by a usb port and maybe an ac adapter if not usb. I dont want 2 usb ports to be taken up to power this drive though or if you know of a good firewire version that would be nice as well so any reccomendations? i would like it to be cheap like 30ish as once it gets high in price, i might as well get a bigger external drive thanks!