Budget - 1000$ to 1200$
Weight Limit - No preference, anything will work
Brand Preference - Since I have very specific requirements, it would be unfair to be very brand specific. But, I believe ThinkPads and HP ProBooks are good.
Battery Life Requirements - 2-3 hrs would be good, more is always welcome.
Aesthetics - No, but poor build quality is a no no. It should not feel flimsy.
Linux and Mac OS X - I would not be able to do without Windows, thats all I am saying.