World of Warcraft is a 7 year old game. Almost any notebook you buy today could run it, even some netbooks!
The model you listed,
Asus- Laptop / Intel® Core™ i5 Processor / 15.6" Display / 6GB Memory / 640GB Hard Drive- Lake Blue
Model: U56E-BBL5 | SKU: 2712418 for $599
Does sound like a decent price for a i5 notebook. I like the 15.6 inchs creen, decent size for gaming and the 640GB hard drive could be faster, but it will still run well.
HEre is a review written by PC MAG guys. http://www.pcmag.com/article2/0,2817,2388309,00.asp
They say the only con is: "Volume doesn't go up very high." which could be solved by getting a pair of headphones.
Oooh it also has WiDi!
USB 3.0 port. WiMAX and WiDi 2.0. Long 7-hour battery life. Powerful Core i5 processor. Aluminum casing.
Volume doesn't go up very high.
The Asus U56E-BBL5 laptop will give you future-proof internal and external components and several wireless connectivity options, all for a sweet price