Some folks think it seems more ecologically sound or something to buy trees that come in pots or bags with more-or-less intact root systems. The theory is that you can use them for Christmas, then put them in the ground, and that way, you haven't killed a tree. The truth is, that you'll probably kill it anyway. Not to say this is a bad idea, only that it's not as easy as it sounds.
Here's a link to our article on the subject:
http://www.familychristmasonline.com/tr ... _trees.htm