Don't get a laptop with an Nvidia 8400/8600 chip. There were articles/announcements recently that alluded to the fact they are all bad, and its likely just a matter of time before they go bye bye.
Nobody is giving clear info on what the problem is, and exactly how extensive it is, but better to err on the side of caution. I am still waiting for Dell support to answer posts about it on their forums.
On another note, if one were to start WoW, would you need to start with the vanilla WoW, or could you go straight to Burning Crusade?