I'm just getting back into snow sports so I bought a pair of North Face Freedom insulated pants (early Christmas present to myself):

http://www.thenorthface.com/catalog/...ated-pant.html

I've only spent two days downhill skiing (first day was about -12C and second day was about -2C) with them and I've worn them to walk my dog for about an hour in -15C temps. I wore midweight thermals under them when skiing and flannel pj pants when walking. It gets quite cold here, and I've been very pleased with how warm they've kept me. If I were to get too warm, they have vents on the sides.

I love the fit. They're not the bulky snow pants of my childhood, the waist adjusts easily with two velcro straps, and I have a lot of range of motion.

I expect they'll be fine for xc-skiing too, but haven't done that in years either so I'll have to let you know.