Wearing white socks with anything but your gym outfit is considered one of the worst fashion crimes. It shows lack of fashion awareness and even worse, lack of style. Socks should generally match the color of your shoes or the color of your pants.
I am not sure what are the origins of this truth, however, the emotions around it are so strong, that i would be very cautious about wearing them. I guess it has something to do with the geeky nature of white socks (that we all wore as kids) or the color contrast/conflict it has with the dark/jeans pants we usually wear. Anyway, you should not look for too much logic when it comes to fashion. Fashions that seem very natural today may appear ridiculous in the future.
A list of references to give you a sense of the level of emotions about it:
http://www.askmen.com/fashion/fashiontip/tip2.html
http://news.bbc.co.uk/2/hi/talking_point/3397149.stm
http://www.fanboyplanet.com/guest/fashion/fashion7-6.htm
http://sg.answers.yahoo.com/question/index?qid=20060915221102AAzvqHD