For what it's worth, I got my wife an
Asus G73 from best buy and it seems to handle 5-boxing better than my usual multiboxing desktop (which I need to have a box fan next to because my beast runs hot). The laptop is a bit bulky, but the big fat fan compartment in the back seems worth it for multiboxing, and I feel less heat 5-boxing on her laptop, than I do with my Dell laptop just working or even playing 1 instance of WoW.
$1250 i7 laptop that works great for 5-boxing. No Blu Ray but whatever, I wasn't looking for that. Actually I bought it for her for mother's day, she just lets me borrow it to multibox sometimes ;)