the video on the pentax is a nice touch, but it is pretty much useless for skiingi agree go with nikon or canonmuch better glass, and when you want to upgrade to a "pro" camera D3s/5DmkII etc., you can still use your lenses
Take a look at the Canon Rebel series as well. I prefer them to Nikon's entry level cameras mainly because I think the layout is a smarter design, but the best thing to do would be to go to a camera store and hold the cameras and see what feels the best. Picture quality will be about the same, especially if you're going to photoshop or something later.