as for majors, it depends. american studies=joke. compsci=not a joke
english, history, philo, ir=seem like a joke, but aren't. i was pretty deep into a philosophy major until a few members left the department and you'd be suprised at the crossover there is with math and cs if you want to even touch on logic. putnam sure as fuck knew math better than most of our math department-there are analytic liberal arts majors. if you're doing some of them, the process to write a good paper doesn't differ that much from sick algebra-it's gotta make sense, you're proving something.

on the whole, the cs/science/engineering guys are going to be a shitload smarter than a womyn's study major, but that doesn't mean the smart guys sitting around in an englsih or quant ec. aren't goint through the exact same though processes to do their shit. if you can think, you can think-it's just numbers scare the real morons. i didn't deal with a whole lot of numbers as an undergrad but i'm dealing with a lot for what i'm doing.