Hello and welcome. I've owned two Shuttle boxes and now an Aria setup. The Aria is much easier to work on and does run somewhat cooler, but it is bigger than the "shoebox" footprint that the Shuttle uses. To some the larger size is a bit of a turn off to the SFF crowd, but I love mine. Here's what I have currently running:
Antec Aria SFF Case
AMD Athlon64 3400+ w/ Zalman CNPS7000A-Cu
Gigabyte GA-K8VT800M m-ATX motherboard w/1Gb (2x512Mb) Corsair TwinX 3200C2Pro w/LED's
BFG Tech Nvidia 6800GT OC 256Mb Video
36Gb WD Raptor 10K SATA
250Gb WD 7200RPM SATA
NEC 2500A DVD Burner flashed to support Dual Layer Media
Sound Blaster Audigy2 ZS
Dell 2000FP 20.1" LCD
Logitech Z-5500 5.1 THX Certified Speakers
The only mods I've done to help with the temperature was to add an 80mm intake fan on the graphics side of the case which helped drop temps by as much as 6c durning load, and I removed the honeycomb fan guard on the rear of the 120mm exhaust fan for the PSU.
Hope this helps,
-E