A couple of things to average. Don't take one as the most important thing, take them all and average them to find out what is important to you.

Get the most you can afford. You won't want to replace your card again in 3-6 months. Also, you pretty much won't be able to use them together unless you get the EXACT same card. And on top of that, WOW doesn't really care about dual cards. I picked a price range that sounded good to me and then looked for a card that fit into it.

Watch for other things you didn't think of. Heat, noise, reliability, power. Some things are worse than others and even if you get the graphics horsepower you want, you might have to upgrade or worry about something else.

This is just me, but go with what you like. I will get flamed for this, but I hate ATI's drivers. Don't like the install, don't like that it feels wonky and don't like where it puts stuff to adjust settings. So I pretty much stick with Nvidia. If you like one brand over another (MSI, EVGA, ASUS, etc) I would stick with it.

Just for history. I started out with a Nvidia 7600, then 8800, then moved up to a 260. I really like it. My next move would be a 470, but everyone says it is HOT and takes a small nuclear plant just for it.

I use Tom's hardware for 80% of my info, along with Engaget and HotHardware.
http://www.tomshardware.com/reviews/...-480,2621.html
Hope that helps and good luck.