Lenovo. Whatever the most expensive 15" is. Lenovo has a decent sale going on right now. $3500 gets you a $6000 machine.

Fast top of the line laptops built for business are expensive up front but when you're on year 7 and its still working and still fast (my $3700 mac book pro)...it starts to make more sense. Even at 5 years you're looking at $60 a month (when spending $3500). Think about all the things you spend $15 a week on to make your life easier. A good laptop is definitely worth it.