Crossfire means running to ATI GPU's in tandem.... The Nvidia counterpart is called SLI (Scalable link interface).
The motherboard you picked, the P6X58D-E, although an extremely good model, is NOT compatible with the second gen Intel CPU's. The P67 on the other hand IS. The P6X58D-E is an X58 motherboard which was designed for the first gen Nehalem CPU's, while the P67 is designed for the newer Sandy Bridge CPU's.
As for hard drives, I recommend the WD Black as the OS drive like someone mentioned above. If you do have the money, obviously go for the SSD, you'll get massively fast start-up times.
Also, for cooling, the Noctua NH-D14 is a really good model, BUT I would choose the Thermalright archon with an additional TY-140 fan. This model would easily beat the D14, but has the advantage of having a really small width. This allows you to use all the RAM slots in your motherboard, which the NH-D14 or any other high-end cooler would almost always block. The archon is really thin width wise, but taller than others. The only thing is that you have to make sure your case is wide enough to accommodate the width of the archon. If you do go with the Archon with another fan, make sure you get a "PWM Y-Cable" for it. You can buy those at NCIX for less than or around $5. Also, if you do get the Archon, I strongly recommend you get the HAF 932 or HAF X case because it allows the cooler to get a fresh air intake from the front bezels without being obstructed, while having enough width for it to fit snugly. I personally have that configuration with the P6X58D-E.
Here are bunch of photos that I took from that build.
Originally Posted by dashaman
If you run your games in window mode no need for crossfire.
Sorry to burst your little bubble, but that is completely untrue. Crossfire or SLI would work for games regardless if you're running in windowed or fullscreen mode.Edited by shinigamibob - 4/3/11 at 5:19pm