I have a substantial amount of experience (professionally) in IT; with quite a few years in network engineer, systems engineer, game engine programming, and application programming. What type of video card do you currently have and what are the other specifications of your workstation? If you are purely a WOW-enthusisat who doesn't play any other games, then your choice on GPU's will be contingent on the rest of your hardware. WOW is a very CPU intensive game engine that does rely on great GPU's, but is not the sole performance granting piece of workstation design. If you have a bottleneck (which I can help you identify once I know the remaining specs) then a higher model GPU will not have a very significant impact. I currently play several games and have a TRI-SLI setup with GTX580's, but I also have close to $5000 invested in my rig. I'm currently running WOW off one of my GTX 580 (WOW's game engine does not support SLI/Crossfire) at 2560x1600 with all settings maxed out. I average anywhere from 110fps in Stormwind to 240fps in 5-man dungeons, 10/25 man raids. The larger the raid the less fps I hit (typically 110 is as low as I get in 25-man DS or FL). My 580GTX are 1.5GB memory cards and the most I utilize is 700Mb of memory on my GPU. However, I soak up a TON of CPU cycles and physical memory for the game itself. My rig is fully water-cooled I7-980X at 4.8GHz, 12GB Corsair Dominator GT 2000MHz, and RAID 0 SSD's--among a lot of other things.
Please don't take this post as a desire to "flaunt" my system--I'm merely showing you that even with a rig I spent a considerable amount on, I've pretty much seen ZERO increase in performance from when I upgraded my rig from a I7-920 and GTX460 video card. Now, if I fire up SW:TOR, BF3, or SkyRim--she gets one helluva work out!
