Best GPU for a 1440x900 resolution

Go for Nvidia GTX 550 Ti version....
If u r not brand biased then EVGA GTX 550-Ti is the best option.
MSI N550GTX-Ti Cyclone ii OC is a beast with a great cooling system
the Asus version has got the highest Overclocked with upto 975Ghz of clock speed.
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but kindly post ur other sys specs like the PSU(most important) and all....
Thanks and Good Luck !!

Here is my system spec: which i am about to buy

Case: COOLER MASTER HAF 932 Advanced RC-932-KKN5-GP ATX Full Tower

CPU: Intel Core i5-2500K or i5-3570k

Mobo: ASRock Z68 Extreme3 Gen3

RAM: G.Skill Ripjaws X Series 2x4GB DDR3 1600MHz

HDD: Seagate Barracuda ST1000DM003 1TB 7200 RPM 64MB Cache

SDD: Crucial M4 CT128M4SSD2CCA 2.5" 128GB SATA III

PSU: CORSAIR Professional Series HX750 750W

I might SLI in the future, so is 750W enough to power 2 GTX 550 Ti??

Absolutely.....it can even run 2GTX 570....dnt worry..just go for it..........i think u can go for a better card..go for 680GTX...cz someday u might thnk of changing ur disp....bt i reckon 550Ti is more than enough for ur 1440X900......
U look at my specs(just like a son in front of urs)...I play Battlefield 3 at ultra at 1080p......

Thanks for the advice.

I'm going to buy EVGA's 550 Ti, I don't plan on changing my display really, maybe in the future I would.

Ya...u r welcome..
N ya EVGA will provide the best 550Ti for u
Good Luck !!