Firstly, leave it in the ground until the last possible minute - it should be the last item you pack, and the first item you unpack!
Between now and when you move it, water it religiously - one good, long soak with the hose (30+ minutes) once a week is far better than daily sprinkling.
When the time comes to move it, if at all possible have the hole it's going into already dug and prepared - dig a good sized hole, put in some manure/compost if possible. Fill up the hole with water, and let it soak away.
Then, when the time comes to dig up the tree, do the following. Slice into the soil all the way round the tree in a circle, at least 2ft away from the stem, or at the very least at least as far as the branches go - the more soil/rootball you take with you, the better chance the plant has of succeeding.
Remove the soil to the depth of the spade on the outside of this circle. Try then to dig under the tree. The ideal you should be aiming for is to have a large ball of soil under the tree - a larger ball of soil than you think - in order to bring as many roots with you as possible.
Wrap this rootball in plastic/sacking as soon as you remove it from the ground (a good way to lift the plant out of the ground is to tilt it to one side, sliding sheeting/plastic under the rootball, then tilt in the other direction, pulling the sheeting through. Then just lift the sheeting, with the rootball on top of it - you will probably need at least two people to do this), and then get it into your newly-prepared hole in your new house without delay - no unpacking first or anything! The less time it is out of the ground, the less it will dry out, and the greater the chance of survival.
Plant it in the hole, to the same depth as it was originally, then firm soil well around the rootball, and water in really well.
You must water well for at least a couple of months, probably a good deal longer at this time of the year, to ensure the plant gets over the shock of being moved - it will need a while to repair damage done to its roots, and to grow new roots. Keep an eye on it in case it suffers wind-rock - if it does, re-firm the soil around its roots.
If the worst happens, and it doesn't survive the move, don't get too upset - conifers don't usually like being moved. Instead, buy a little christmas tree to celebrate your first christmas in your new home, and plant that afterwards instead!