This is my current (as of October 2013) gaming rig. Over the years, I've taken the approach to upgrade "here and there" as I felt a need or experienced a game-stopping issue that could be addressed with a part replacement.
Assorted parts buried within this rig actually date back to 2005, though most things have been replaced. I did a major rebuild in 2008, but about all that remains from that build is the Antec Nine Hundred. 2009 brought along the hard drives (non-SSD) and dual Westinghouse monitors. The Radeon 6870 was a 2010 purchase that has held up remarkably well. 2011 brought the ASUS monitor for some great Eyefinity fun. In 2012, I replaced my dying 2005 Logitech MX518 mouse and G15 keyboard with a Razer Imperator and BlackWidow Ultimate Stealth. I also added the OCZ SSD when doing a Windows 8 fresh-install. Finally, in 2013 I added a second SSD (the Samsung), replaced the existing 8GB RAM with 24GB and upgraded the power supply to the HX750 in preparation for a new video card purchase I hope to have in place for Battlefield 4.
My gaming interests are pretty vast, but I spend most of my time in racing games and Battlefield 3. This system runs BF3 at about 45-60 fps on High, which meets my personal minimum comfort level; however, it suffers on high with Eyefinity turned on, so I will usually run at Medium when using all three screens to maintain 45+ FPS. (I get about 65-85 FPS on Medium and a very uncomfortable 20-25 on Ultra with a single 1920x1080 screen).