Pentium Core 2 Duo Wolfdale 3.0ghz - works flawlessly (obviously).
Asus P5Q Mainboard - works great, except the onboard ethernet chip requires a little configuring to get going.
EVGA Nvidia GeForce 8800 GTS 512MB - Works flawlessly using EnvyNG to install the proprietary driver.
Western Digital Caviar SE 250GB SATA drive - Works great, but does require SATA mode to be set to ACHI in the BIOS (as will all SATA drives if I'm not mistaken).
4gb OCZ DDR800 ram (2x2gb) in dual channel mode - works flawlessly.