My personal favorite windpants are Mountain Hardwear Transition pants(worn over a pair of Patagonia Cap-1 pants). They breathe well, have a good DWR coating, and a Gore Windstopper membrane which makes them about as close to windproof as anything I have ever seen. They definitely shed snow very well and I use them in rainy weather as well. They are not waterproof, but with the rain striking them at an angle, most of it dribbles off, and most of what makes it through gets expelled as water vapor along with my perspiration. At the end of a day, I am occasionally damp, but never soaked. They are not adequate for a torrential downpour, but that doesn't often happen in snowshoeing conditions. In any case, I carry a pair of Golite Reeds(4 oz) just in case things get sloppy. On my upper body I wear a Patagonia R1 Hoody and a Mountain Hardwear vest. This is great for all but the heaviest snowfall, or if it turns to rain. Then I just slip into an Integral Designs Event shell about 80% unzipped for ventilation and keep on truckin'. All of this said, there lots of great windpants on the market, but I don't think most of them breathe as well as the Transitions. They are a lot lighter, however. The Transitions weigh ~ 8 oz(size M), but I don't even notice. Bottom line: you can dress a lot lighter than you might think when you're on the move, especially snowshoeing, which really puts out the heat. Hope this helps.
Oops, just noticed Paul's post, above. Montane Featherlites would also be a great solution.