I've been using a light box for a couple of years now, along with forcing myself to spend more time outside even when it's cold. It's definitely made a difference. My husband can always tell if I skip my light box for a couple of mornings in a row, because I get really lethargic and cranky.

I'm a big supporter of this company: http://www.sunbox.com/. It's a little more expensive, but I believe they have a lifetime warranty. If you do buy a light box, first do some research to be sure you're getting the right thing. Generally you would want a light that is 10,000 LUX. I use this one: http://www.sunbox.com/products/sunlightjr.html.