Macs are weaker too.
The laptop you posted would wipe the floor with any ibooks available, that's for sure. The hd mobility 5870 is beast.
Also, microsoft office works better on windows from what I've heard, just like how itunes works better on OS X.
Running bootcamp would add the cost of buying the windows OS, an added cost.
Also, congrats on getting into Duke!
I have a few friends going there next year, maybe you'll be in the same classes!