Space was part of it, but I really don't care that much. The P series shuttles run at about 27 db, which is quite quiet. I actually like the antec p180 cosmetic better then the shuttle, but the smallness and everything about the shuttle is why I bought it. I'm not really worried about the expansion options, right now, I only use one PCI slot and that is for my tv tuner, I've really never had a need for anything more then that, besides that, nearly everything that I want is made with a USB version, and with the 8 USB ports the shuttle has, I doubt I'll run out. (4 on back, two infront, two inside). Once you own a shuttle, you'll know why people like them. They are very nice in build quality and the engineering that goes into them is amazing.