Advice on Video card upgrade

heya this is my my current comp setup and am looking at a big video card upgrade , since i live in canada and quadcore prices are still a bit too much till perhaps next year . anyways with this current setup and a 275$ budget what would be a good video card upgrade .

Motherboard:Asus p5k/epu
Cpu:intel e7200 2.5 ghz
Video Card : Ati Sapphire 4670 gddr3 512 meg pci-e
hard drive:seagate 500 gig sata 16 meg cache
memory:4 gigs ddr2 800 mhz oca reaper hfc series
psu:seasonic M12 600 watts atx 12v
operating system: windows xp home

there you have it folks

P.s. By the way a few friends have recommended me to either buy one of these cards from my local computer store , But i wnat to get feedback since many have suggested me to go to tom's hardware for adviceanyways here are the links to the two mentioned cards

1:http://www.newegg.ca/Product/Product.aspx?Item=N82E16814127443
2:http://www.newegg.ca/Product/Product.aspx?Item=N82E16814127439

thanks for the advice , i think since its not much in stock right now by the time it is in stock i'll have the extra money to buy it , i wont be able to take advantage of the direct x 11 since i am stuck on windows xp but since i'll be upgradeing to windows 7 and a new cpu next year . i have to say this card is worth it