If you are going to SLI(or would like to at some point) I would recommend the 1gb version of the card. Of the versions I'm seeing in stock I would get this;http://www.newegg.com/Product/Product.aspx?Item=N82E16814125333
The card can OC a good 30-35% usually. You may want to just get one, OC it and decide if you even feel the need for another. When/if you do get a second it tends to scale very well.