Don't throw out the Christmas tree or abandon it in a back lane, (as too many unscrupulous types are wont to do). Instead, lop off the branches and prop them around vulnerable plants to protect them from frost. Or, if you're feeling madly creative, like a friend of mine, keep the tree until spring and grow sweet peas up it. This would be a lovely idea for a children's garden - to teach the ideas of recycling and interdependence in one go. Or perhaps you might try runner beans, and add the concept of food-production. If these ideas don't appeal to you, then chop up the tree and use it for kindling when it dries in a few weeks.