In reply to mark burley:
I have been snowboarding and mountaineering for ages and have tried pretty much every combo there is I think!!!
The HH Lifa range are always a good choice for base layer but if you haven't yet tried Howies merino base layers then I can honestly say you don't know what you're missing! I'm a huge fan of Howies but their base layers are without a doubt the best I have ever used and when it's cold they keep you brilliantly warm, they don't smell even with constant use and they wash up brilliantly. They are a little more expensive than some due to the quality but it's definitely money well spent and you really do get what you pay for.
Some of the best fleeces I have are from 66 North but you have to order these over the net as they're an icelandic company.
I also have an ME shell but I keep this purely for mountaineering, when on the slopes I always wear a fleece lined boarding jacket as I find this works far better in terms of warmth and performance.
Enjoy your trip!