antec aria case fit mini atx case, be careful its very cram, so you would need round IDE cable.
i don think shuttle is much more space efficient
btw, i've built one for my friend with antec aria case with the following spec:
athlon 64 2800+
MSI mini atx board (forgot which one)
MSI 9800 PRO
PC3200 1 gig ram (i believe the mobo didnt work with 1 gig ram, he has to RMA the other one)
seagate 120 gb hdd
NEC DVDRW
warning:the case is very tight and bad for cooling