I commuted the 4 miles from the apartment to campus when I was in college, and did some mountain biking on the side. Nothing fast, but some mud. I learned a few things doing that:
-a moped is fun in summer, but way too cold to ride in winter
-winter temp of 20F isn't a bad temp to ride in
-plastic shopping bags, when put over the handlebars, work really really well at keeping your hands warm at these temps. Way better than any heavy duty skying mitten. However, it does look a bit funny...
-winter temp of 10F is probably too cold though!
-don't leave your bike out in the winter. The seatpost will freeze up. [I lucked out, and it was at the right height!]
-you can put a week (or two?) of laundry into the basket, and bike to the landromat, but the bike will handle funny
Then I left college, gained 45lb, got married, had kids, and am now trying to spend more time out of the house. Well, maybe not; but I'd sure love to lose that weight and get back into shape.
My bike, then and now, is a Gary Fisher Advance, which I think is about worn out. Seatpost is frozen, chainrings are showing heavy wear, headpost(?) is loose, bottom bracket might be worn too, and the chain is stretched to 3/32's, maybe more. Plus, in full commuting form it weighs 39lb.
I'm not sure yet what I will replace it with, probably a hybrid, although I've been doing a lot more road riding lately. Haven't gone bike shopping yet though, just looking online a few times. I also have to figure how to get some more riding time in, I live 50 miles to work, and there isn't a good park and ride at a good location--at my fitness level, 14 miles is way too far!
Anyhow, that's my into. Nice to meet you all. Time to go ask some questions in the general forum.