Hi,
Battle Honours do Soviets in snow gear which are quite nice although you will probably have to order them from the states. Nice figures.
Baker Company do both Soviets and Finns. But I'd have to say im less than impressed with the quality of the sculpting of the Finns, cant speak for the Soviets though. The Sovs are in peaked hats.
The Winter War is a little side project for me at the moment, I'm just assembling my figures, vehicles, etc for it so I'd be interested to see what you pick.