Agree with Eric, but just with the caveat that you'll need to think ahead to getting home- putting on all that wet stuff at the end of the day is kind of gross. I usually pack an extra pair of socks (so, bike in clothes & shoes that get wet, pack dry clothes & shoes for work, plus pack dry socks for biking home...maybe a moot point if you wear socks to work).
Also, I usually just wear regular sneakers & socks. (I've never heard of waterproof socks!!) My roommate has a newspaper subscription, so we have a bunch of those plastic bags. I will put my socks on, then put one bag on each foot before putting my shoes on. I usually need to tie the bag to my ankle to get a decent seal on top.