I buy from the awesome www.auspcmarket.com.au
My Current system which I built rather cheaply consists of:
Pentium 2160 @ 3.0ghz (Dual Core, based on the Core 2 Architecture)
2gb of memory
Crossfire 3850's
But here goes:
Processor: Intel Core2 Duo E6750 2.66Ghz, 1333mhz FSB, Dual core - $253...