Just so you all know, BC is the farthest place from dry you will find in North America... well maybe not quite but it's hardly a dry cold. It's a very damp cold.
But Whistler is some of the best skiing/boarding in the world. I havent actually personally boarded up there before (even though I'm only about 2 hours away) it's just too expensive for a day trip. But lots of my friends swear by it and I know there are people that wont ski/board anywhere else.
Lots of terrain, friends have told me that you could take some runs from the very top to the bottom/village that'll take you 45 minutes to get down without stopping. You will love it, I'm sure. Just dress warm, it gets cold at the top (although we are getting unseasonably warm weather, right now)