I was a computer technician in college (last year), and I have a couple of recommendations for things that you need to look for in a laptop if you want to use it for gaming.  

#1 make sure that it exceeds the Recommended system requirements for the Burning Crusade (they're higher than the current WOW requirements)

#2 Laptops SUCK to try to upgrade (with the exception of RAM) so get what you want fron the start.

#3 Laptops have the graphics card built into the motherboard, so make sure it has an NVIDIA or ATI label because the rest are a lot lower quality.

#4 brands to stay away from if possible: HP, SONY, Compaq, and anything that you've never heard of before.

#5 if you use wireless, make sure that the laptop's built in card supports the type you use.

I don't know what your price range is, but the following websites 
http://www.newegg.com
http://www.tigerdirect.com
have a wide selection for you to explore (I have ordered computer parts from both sites multiple times and had no issues.)

Hope this helps  :wink: 

btw, Apple has the best quality laptops, and the new ones with the Intel chipset can be set up to run windows OS if thats your thing...