Motherboards with Extreme Gaming with the Intel® Core™ i7 Processor Extreme Edition is meant for a user like you. It can provide very immersive gaming experience. You can refer to more on the following link http://www.intel.com/Consumer/Learn/Desktop/corei7-extreme-detail.htm.
More specifically, Core™ i7 975 processor with DX58SO motherboard is the best performing combination as of today. Both of them are high end parts and deliver superlative performance. Lower end Core i7 on similar motherboards are also an option i.e.: Core™ i7 CPUs (950/940/920).
First things first, gaming performance is largely dependent on the video card rather than on the CPU ! Now, u should decide on a video card first followed by the CPU & last on the latest chipset ur CPU would support !
Your choice of video card (GPU) should be dependent on the size of ur current display(LCD) or the new display that u might be considering to get for urself ! 22" inches is the minimum size u should get if u want to really enjoy ur games. Higher the size of the display, higher the resolution which will require a more capable video card. U should see that the optimal resolution of ur 22" display should be Full HD ie. - 1920x1080 which is a norm now-a-days.
For a 22" inch display u should atleast get a Nvidia GTX 295 or 285 or atleast a 275 OR ATI 4890 1GB or a 4870 X2 to be able to handle the high resolutions whithout any drops in frame rates.
Now, as far as the CPU goes, the only thing to remember is to zero-in on a CPU which would not create a bottle-neck in the gaming performance of ur entire system. A high end dual core such as a Intel Core 2 Duo E8400 would be a fair addition to ur rig considering that u might wanna spend handsomely on a good video card & not on a costly CPU. But if u wish to be on the safe side by being future proof for 2 yrs or so, u should atleast go for a mid quad core - Intel Core 2 Quad Q8200 CPU paired with a nice Motherboard based on the Intel P45 (Northbridge) chipset or upwards like a X38 based board or a X48 which would only take DDR3 RAM ! For such high-end boards, also see if it has multiple video card slots. U might wanna atleast get 4 GB RAM to do justice to ur gaming rig.