How's this build, and help me choose an MB?

I wanted to build a new gaming rig from scratch, and I'd like some feedback on what I have so far. I haven't chose a motherboard yet and that's what I need the most help on. I'm willing to go to $220 for a motherboard, and also some feedback on the other parts I've selected would be nice. Thanks in advance!

Motherboard
???

CPU
Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) 4 x 256KB L2 Cache 6MB L3 Cache LGA 1155 95W Quad-Core Desktop Processor BX80623I52500K ($220)

RAM
CORSAIR Vengeance 12GB (3 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMZ12GX3M3A1600C9 ($95)

Video Card
*TWO* (Yes, I need TWO of this graphics card) SAPPHIRE 100314-3L Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card ($175 $350 OVERALL)

Sound Card
ASUS Xonar D1 7.1 Channels 24-bit 192KHz PCI Interface Sound Card ($90)

HDD
Western Digital Caviar Black WD1002FAEX 1TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive ($75)

Case
Antec Three Hundred Illusion Black Steel ATX Mid Tower Computer Case ($50)

Power Supply
CORSAIR Professional Series HX750 (CMPSU-750HX) 750W ATX12V 2.3 / EPS12V 2.91 SLI Ready CrossFire Ready 80 PLUS SILVER Certified Modular Active PFC Power Supply ($150)
 
Back