If you want to follow B-school fashion trends, then go for the ubiquitous Patagonia, Columbia, North Face, REI, etc. gear. Get a high tech jacket + fleece combo. Bonus points for IPOD/Iphone specific pockets / zippers, branded fabrics and fair-trade certified production. Check this out for further guidance.
https://stuffwhitepeoplelike.wordpress.c ... e-clothes/Note: While it refers to "white people" I'd say it's applicable to most B-school students regardless of race.
If not, you can just buy any other jacket (as long as it's warm and water and wind proof), gloves, scarves and pullovers.
Either way, you will definitely need a thick overcoat to wear on top of your suit when recruiting.
As far as trousers go, jeans can get cold unless wearing long underwear. If you want to avoid those, then try some corduroy pants.
L.
PS: not in Chicago, but in Boston, which is similarly cold, albeit less windy.