anyone that says shuttles ain't got the full expandability of an atx case is lying tbh, just finished squeezing in my 3rd hdd giving me 280gb of space.
Running those three plus a 9700pro, and o/c'd xp2700 and a cd-rw/dvd combo drive all off a 200w psu.
And there's still space for another hdd. Space for expansion gets thrown up as one of the bad points to owning a sff system all too often and imo its complete rubbish.