Purchasing a new computer - Is everything going to be compatible?

I'm new to this, so I'm wondering if this is a good setup. Is anything wrong with this build Will it actually work, and run most games? What do you think about it, I'd appreciate any opinion on it.

Case ( PSI CycloneX Gaming Tower Case - Silver/Black )
Processor ( Intel® Core™ i7 920 Processor (4x 2.66GHz/8MB L3 Cache) )
Motherboard ( Asus P6T -- Intel X58 Chipset CrossFire and SLI Supported w/7.1 Sound, Triple-Channel DDR3, Gb LAN, S-ATA Raid, USB 2.0, 3-Way SLI PCI-E MB - 3-Way SLI )
Memory ( 6 GB [2 GB X3] DDR3-1333 Triple Memory Module - Corsair Value or Major Brand )
Video Card ( ATI Radeon HD 4890 - 1GB - CrossFire Mode (Dual Cards) )
Power Supply ( 1000 Watt -- Extreme Power Supply - [Gaming Series] Quad SLI Active PFC )
Processor Cooling ( Thermaltake V1 CPU Cooling Fan System Kit - Silent & Overclocking Proof = Maximum cooling efficiency for quietness and performance )
Video Card Brand ( Major Brand Powered by NVIDIA )
Primary Hard Drive ( 320 GB HARD DRIVE -- 16M Cache, 7200 RPM, 3.0Gb/s - Single Drive )
Optical Drive ( 22X Dual Format/Double Layer DVD±R/±RW CD-R/RW Drive - Black )
Sound Card ( Creative Labs Sound Blaster Audigy SE )
Network Card ( Onboard LAN Network (Gb or 10/100) )
Windows Vista Home Basic 32-bit

iffy? so is 1000W not enough?

would a single 5870 be better than 2 4890's? I'm primarily going to be playing games with this rig, from Crysis to the soon to be released L4D2 and on.

Any one else care to chime in? Any help is appreciated greatly.

here are the specs on it

Type ATX12V / EPS12V
Fans 1 x 140mm fan
PFC Passive
Crossfire Ready
SLI Certified
Modular No
Efficiency 80 PLUS Certified
Dimension (L x W x H) 7.0" x 5.9" x 3.4"
Connectors 1 x Main connector
1 x 12V (4pin)
1 x 12V (8pin)
8 x peripheral
8 x SATA
1 x Floppy
4 x PCI-E

Are you building from Cyperpower PC? Based on your post, it looks like it to me. What is your budget and I would recommend you build your own, if you are having it built.