Please help!

WoW on both laptop - ok

Diablo - maybe on Toshiba t low settings. (Have AMD 6630 w/ i7 and sometimes is laggy).
Diablo - not ok on Acer. Friend has i7 with intel graphics and Diablo won't run.
 
If you keep it to trusted retailers, it is really the only way to go.
You can find nearly everything quite a bit cheaper online.

Newegg is one of the best North American online retailers.
Their service is excellent and, in the case you do have an issue, their customer service is great as well.
I have no reservations recommending that you purchase from them over Target (online or in store) :)