Well, here's a post from a guy who used to ride 700Cx35 studded (upgraded to 700Cx45 recently) and who has some *ahem* experience in winter cycling: consider going singlespeed. FG might be a long step, but singlespeed shouldn't, and it works fine for small commutes up to 10 miles. You don't need a separate freewheel, you can use one of those cheap freehub-conversion kits.

I commute to work on a singlespeed, all season.

EDIT: or wha Steev just said, get a hub gear. This solution is a bit more expensive, though, and requires the wheel to be rebuilt, probably a new set of spokes, too.