Yes, AMD 4-life.

Isn't the 7990 very expensive though? Plus I probably would get problems with micro-stuttering.

My rig is pretty disapointing at the moment.  I need to get it upgraded soon.

AMD Athlon II X4 635 @2.9 GHZ not overclocked.  
4GB DDR3
I had a GTX 570 EVGA Superclocked FTW Edition but it died from extreme underclocking and voltage lowering.  (It gets so hot in the room I was trying to cool it down).   I have my old Gigabyte GTS 250 atm.  I can game with moderate graphics.  Once you get used to it it's not too bad.
750GB HDD
I think my PSU is 750W
24" LG Monitor 60Hz

I built my last one in 2009 and it was cheap even then, but it has low power consumption:

AMD Athlon 64 X2 5050e
Mobo Asus M3A78-T with Radeon HD3300 onboard GPU with 128MB dedicated graphics RAM (+512MB assigned from the main RAM). In its times HD3300 was the fastest onboard GPU, I chose it to be able to choose a GPU later... Well, later has become a few years! 
4GB RAM ECC
500GB SATA + 250GB PATA HDDs (when I still used Win XP I was forced to keep a PATA drive because XP, even building an install disc with updated drivers, had problems with my Mobo chipset/SATA drives combination)
DVD burner
Kubuntu 12.04 LTS + Windows 7 dual boot
Enermax Pandora case with two low noise fans blowing filtered air inside (I replaced the fan provided with the case and added another one)
Low-noise Cooler Master 400W PSU (bought separately, I wanted a low-noise one, so I bought a case without PSU)
Asus 22" 1080p LED display
Logitech Wingman Extreme Digital 3D Joystick
Flexiglow Cyber Snipa game pad
Trust Predator GM-3500R Force Feedback Steering Wheel with 2 Pedals
Universal Pro-Driving Simulator adjustable support for steering wheel and pedals
Several external USB HDDs, one of which is usable also as a standalone multimedia player.

As of now it can run almost all the games I play or I'm going to play in the near future well enough for my tastes, as my backlog is quite behind in the years, but I'll have to upgrade at least the GPU for The Witcher 2 (the only game in the last years that I bought shortly after launch, without waiting for a budget edition). Before upgrading the GPU I'll wait for a little more graphics power to become available on low power consumption GPUs.

Alas all my efforts to make a low-noise PC are partially ruined by an UPS with a small, noisy fan: it's more noisy than the PC itself with its 4 low-noise fans (PSU, CPU and 2 cas fans).

i7 3820 - 4.2ghz OC
Asrock X79 Extreme 6 mobo
8GB DDR3 1866 mhz G.skill Ripjaws
Nvidia GTX680 2GB - Stock OC
NZXT Phantom 420 Case
250GB Samsung SSD
1.5TB Hardrive
Corsair H100 Liquid Cooler
PC Power and Cooling Silencer Mk II PSU 950w
Windows 8

I would show a picture, but apparently I spend way more money on PCs then buying cameras.

My old gaming rig ran a 9800gtx. I chose AMD for my new rig because I'm on a budget and recently AMD has a much better performance to cost ratio on their midtier cards. I'm assuming a lot of other people had a similar rational. If money was not an issue I wold have continued using nvidia cards.

i7 2600k
gtx 550 ti
8gb

8 TB for what? O.o

Well, back when I build my PC the only sensible options were the HD5850 or the HD5870 as Nvidia cards, the GTX470 and 480 used a lot more power, were hotter and weren't a lot faster than the AMD counterparts.

And that's what I will look for the next time: performance/price, power consumption, heat and noise.

Here's my laptop specs. It's not the best, but as my first gaming/general use PC, it gets the job done and exceeded my expectations.

Dell XPS 15 (L502X) - with multitouch screen (it kinda sucks) and backlit keyboard

i7 2760 QM CPU 2.4 GHz

6 GB RAM (1GB dedicated to video RAM)

NVIDEA GeForce GT 525M 

64 Bit Windows 7 Home Premium

I'm actually surprised how many people don't use Windows 8. Less resources used up was a surefire reason for me to get it. Just takes some getting used too but definitely not as bad as I had heard people raging of.