I can't quite pledge to bike all winter but I'm certainly going to try! In Buffalo, you can get a foot or more of snow overnight and expect to still go to work like everyone else even if the plows haven't hit all the roads yet! I'm still not sure what to expect, last winter was *very* mild so this might be the first real winter in this house, which should get less lake-effect snow than where we moved from. Also, I don't think our (relatively quiet, residential) street was plowed once last year - I ride on streets very similar to ours all of the way to work. It could be good if I don't get salt all over my bike but it could mean lots of inches of snow to ride through!
What I'm trying to get at is: I've decided that at the very least, I have to consider riding every single day. Even if there is a snowstorm and I drive for a few days, each of those days I have to question using my car and bike if at all possible. That is my pledge. Driving has to be the exception, not the rule, for all of winter (even if by some craziness I drive every day) Biking is considered first.
I got a nice rain jacket from nashbar when I started riding for about $30 - very worth it. It has a hood that fits over my helmet and a long back to cover my butt while I ride, and it's pretty lightweight. I just recently bought rain pants for $20 and they're awesome but I haven't had a chance to use them much yet. I think it's better to be comfortable on the ride to not get discouraged from riding (I've done the wet pants thing a couple of times and that sucks even if you have something to change into!)