oh, and your best friend (which is too late to help you now, nootch) will be
http://www.ratemyprofessor.com . the downside is it's difficult at times to gauge exactly how a prof is... sometimes the only people who rate them are the morons who flunk out (omg, the outrage, I didn't go all semester and you won't give me the 500 bonus points I need for an A? YOU SUCK!), and good students rarely rate the profs... and there's always the rare good teacher that will have a personality that doesn't quite mesh with yours... but it's a good general tool to have at one's disposal to see if the prof is a total nightmare.