Cold rain I don't mind. True freezing rain as in an ice storm is the only thing that put me on public transportation last winter (3 or 4 days, I think it was).

Last spring I built up a fast commuter (a cross-style bike) which I ride all the time now. My old ride (which I sometimes refer to as the boat anchor) is about to get a good overhaul and be repurposed to my winter bike (complete with spikes). That should see me through anything but several feet of snow (pretty rare in DC). We'll see...