Is this graphics card good enough to play WoW.......?

Barely. If you try to walk around Dalaran after sundown, or party with more than one Death Knight, you'll notice some serious Interface lag. And with the WotLK instances, if you try to turn down spell effects to compensate, there will be boss fights that you won't be able to complete, because you'll need maximum spell effects to see the AoE's that will be used.