Since I never throw away my computers unless they break completely (in which case I cannibalize whatever parts I can), I have about 5 fully functioning computers in my house. My gaming and video/photo editing workstation PC is as follows:
Case: Cooler Master HAF 932 full tower(not the prettiest of cases, but the cooling is great)
Mobo: EVGA Nvidia nForce 790i FTW
CPU: Intel E8400 3.0Ghz (OC'd to 3.5 ghz stable and cool)
RAM: 6Gb DDR3 1600 (I have a 64-bit OS, so the extra ram is actually useful)
GPU: 2x XFX Nvidia GTX 260 Black Edition (back when I bought these, an individual black edition got the same benchmarks as a GTX 280, at the time the most powerful card on the market. They were also less than half the price, and cheaper than even a far weaker AMD/ATI equivalent.)
HDD: 1Tb 7200RPM
24" Widescreen Monitor (1920x1200 native. I can't stand that stupid 1920x1080, it just seems... wrong.)
I bought this back in December, it cost under $2000 (including the monitor), and it still absolutely destroys any game I throw at it on highest settings. Take that, people who claim a PC needs to be upgraded every month!