First Time Gaming/OSx86 build

Instead of buying a new Imac, I thought I'd take the $1,700+ and try for a homebuilt gaming PC with possibilities of becoming a hackintosh down the line.

Please let me know what you think of this build. I'm less concerned with bargain hunting than finding a setup that will actually work for me as a first-time builder.

APPROXIMATE PURCHASE DATE: this week or next

BUDGET RANGE: up to $1,800

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: gaming (mmorpgs), photos, music, office productivity, internet

PARTS NOT REQUIRED: keyboard, monitor, OS

PREFERRED WEBSITE(S) FOR PARTS: newegg.com

PARTS PREFERENCES: i7 920 and gigabyte ud5 board (supposedly work well with OS X)

OVERCLOCKING: NO

SLI OR CROSSFIRE: Yes


Case:
Antec Nine Hundred Black Steel ATX Mid Tower Computer Case
http://www.newegg.com/Product/Prod [...] 6811129021

Processor:
Intel Core i7 920 Nehalem 2.66GHz LGA 1366 130W Quad-Core Processor Model
http://www.newegg.com/Product/Prod [...] 6819115202

Motherboard:
GIGABYTE GA-EX58-UD5 LGA 1366 Intel X58 ATX Intel Motherboard
http://www.newegg.com/Product/Comb [...] mbo.236242

Power:
CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power ... - Retail
http://www.newegg.com/Product/Prod [...] 6817139006

Memory:
CORSAIR XMS 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 Desktop Memory Model
http://www.newegg.com/Product/Prod [...] 6820145259

Graphics:
2x SAPPHIRE 100279-1GL Radeon HD 4870 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card
http://www.newegg.com/Product/Prod [...] 6814102849

Hard Drive:
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
http://www.newegg.com/Product/Prod [...] 6822136319

Optical:
LG DVD Burner Black SATA Model GH22NS50 - OEM
http://www.newegg.com/Product/Prod [...] 6827136167

Wireless card:
Rosewill RNX-G300EX IEEE 802.11b/g PCI Wireless Card Up to 54Mbps Data Rates 64/128-Bit WEP, 802.1x, WPA, WPA2, AES, TKIP ... - Retail
http://www.newegg.com/Product/Prod [...] 6833166020

Cooling:
ARCTIC COOLING MX-2 Thermal Compound - Retail
http://www.newegg.com/Product/Prod [...] 6835186020

Right now I have a 1920 x 1080 monitor

Would one card be sufficient? Then I could upgrade later if I ever got a larger monitor.

However, I'm also thinking about buying a 1920 x 1200 monitor with this build, depending on how much I have within my $1,800 budget.