+1 I set up a 1990 Trek 1400 on my mag trainer- mainly because it already has a rear wheel pickup for the odometer. Tough on the rear tire after a while too.

I'm set up in an unheated room above my garage so I still layer and need to be bundled up pretty good at the start. It got to a whopping 11 degrees here today! If the roads are clear of ice and snow I'd much prefer to take the mountain bike out for a real ride. The trainer is nice to somewhat stay tuned up but best for getting a bit of a head start when if finally thaws out.