Fenders, definitely.


How long is your commute? For 30 minutes or less a decent rain jacket (Showers Pass Transit, for instance) and polypro tights might work. Much longer than that, and you might look at Rainlegs or water resistant tights.


Jackets usually need to have good vents to keep you from getting soaked in sweat. That'll also be a problem with waterproof tights or pants. Wind and hard rain (say, 1"/hour) will push you to waterproof; light rain and little wind are easier to handle.