Help on vid card pick!

Hi everyone,
I am building a new computer and have purchased everything but my video card. I was hoping that someone could run through my specs really quick, and recommend a card that would run well with the other hardware I've bought. I've been stuck on this for a while now and I want to buy the perfect card. I was very close to buying Sapphires version of the Radeon HD 4870 when a guy at the office told me to never buy off brand manufacturers. He recommended to get the Ati version of the same card. I then pondered going the Crossfire or SLI route but my budget is around $350 and that can get more expensive.
Somebody please straiten me out! I want this machine to be fast and it has been 6 years since a built a system and I am very excited about this one. Here are my specs:
Mobo- ASUS Maximus II Formula LGA 775 Intel P45 ATX
CPU- Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Quad-Core
RAM- mushkin XP ASCENT w/ eVCI technology 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel
PS- CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC
Hard drive- Seagate ST3640323AS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s
CPU fan- EROtherm Nirvana NV120 120mm 2-ball UFO Bearing / Transparent
Case- LIAN LI PC-65B Black Aluminum ATX Mid Tower
Graphics Card- ??

There should be nothing wrong on buying from Ati's manufacturers, they usually stick to the reference design given by Ati. The general consensus is that Sapphire is Ati's #1 partner, but that doesn't mean that the others are any bad, I bought a Sapphire card earlier this week and I'm hoping for it to arrive in the next few days.

If you for some reason don't want to buy a Sapphire branded product, then look for Visiontek, MSI, or Diamond.

I forgot, given the fact that you already have a crossfire capable board, then maybe you could also take the 2x HD 4850 route for $340.

SAPPHIRE 100245L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail

http://www.newegg.com/Product/Prod [...] 6814102770

Not really, for a computer screen you will be using DVI instead of HDMI. DVI carries only digital video, while HDMI can carry digital video and audio, but since you will have speakers/headset on a computer for the audio, there's very little reason for a computer screen to have HDMI.

Look at the res he will be playing: 1680x1050.

So, CF at that res doesn't take ALL the bandwith from the X16/x16 and the 8x/8x holds on equally.

Now, that leaves no room for bigger res!

If you don't plan on going onto a bigger screen anytime soon (prolly before your next hardware change) keep the P45 and CF a couple of 4850's and have a blast IMO

Now, the single fastest card can also be a good choice, but not taken into consideration the "P45 not being capable", but a power/heat issue inside your rig.

Maybe a 4870/GTX260 is also a good choice and they'll last till you want to change your rig.

Esop!

EDIT: Spelling xP