Arkay's been great about editing
my old post, but I thought I'd re-post because it's ended up a little confusing
Case: Antec Fusion v2 Remote Black
Power: Corsair VX-450 450W
Motherboard: Gigabyte GA-MA78GPM-DS2H mATX
CPU: AMD Athlon 64 AM2 Dual Core CPU 4850e
RAM: Corsair TWIN2X2048-6400 2GB C5DHX
CPU Cooler: Scythe Ninja Mini
Optical Drive: ASUS DRW-2014L1T 20X DVD±R/RW SATA LightScribe
Storage: Samsung 750GB 7200rpm SATA II HD753LJ
Tuner: AverTV DVB-T 771
Components were selected based on price and quietness. Thanks to the Scythe cooler there's only three slow 120mm fans in the system - the case and the Corsair PSU. The case has rubber mountings for the HDD. The ASUS DVD drive - which is apparently already pretty quiet - will be set to run slow with some simple hdparm settings.
Everything except the cooler is coming from cpl.net.au. The Scythe is coming from pccasegear.com.au
Total system cost: $856! (this doesn't include the tuner which was $70 three years ago)
I'll be installing mythbuntu and XBMC.