if you don't wanna deal with studs or the possibiltity of falling down i say you gotta wait till the temp goes over bacxk up over freezing during your commutes.
that said, i dealt with the possibilities of falling last winter riding a road bike with slick tires and only came close once (here in PA snow is not a major issue). but this winter i have a longer commute so i bought some studs with a spare wheelset.
you really gotta just go out and ride your commute in some real crappy conditions when your prepared for the worst to figure out how bad it gets....
finally, if you mountainbike at all you may find increased challenge of riding in crappy weather finally gives you the thrills you only thought you can get off-road!! watch for cars though, none of those in the woods.