Well I don't often post, mostly just glean info, but I have done ALOT of Fixed winter commuting!

First off, fixed is the way to go in snow, but more importantly with small patches of ice it really gives all the feedback you need to stay up, saved my butt more than once!

The bike I've used is an old Peugeot that I use a 700c studded tire in the front and an unstudded cross tire in the back. I found that studded in the rear didn't help enough to warrant the increased weight and rolling resistance. The first wheel build I used was a Sturmey Archer S3X, but it only held up for about 1000 miles, which didn't make good sense for the price of it. If you wanted a three speed option I would check out Sheldon browns site and use his instructions to rebuild an old Sturmey Archer hub into a fixed hub, guess they hold up much better. What I use now is a Surley Dingle fixed cog, it allows for two gearings one for the clear days and one for the snowy or windy days. Used it all last winter and found it to work out well.

Goodluck with you build!