I don't wear waterproof pants when i snow shoe or X country ski. I have a pair of wool Ibex pants that are water resistant and very warm. I wear them for the above activities and for cycling when it is 40 or less degrees. I fall a lot when skiing, and I've never been soaked through. You should look in the Athleta catalog for waterproof pants. They are having a big sale now on that stuff. Sierra Trading Post also has a lot of this stuff, too, but it's a search to look through their web site.
No snow here, another day of cycling... I think Al Gore is right!