Yes, buying a "daylight" lamp is a good idea.
I'm not suffering from SAD, but I too like summer better, mostly because of the energy costs winter brings in a land where you are mostly confined to the house, unless you enjoy freezing.
Did you know that you can also affect this affective disorder with food, colors and ethereal oils?
Sunlight increases the Serotonine level in the body. (Happiness hormone)
Sunlight and some food helps to increase the Serotonine production when it goes down in winter.http://wiki.answers.com/Q/What_foods_ra ... evelsheric
Colors: Orange and yellow cheer up.
Eating oranges and enjoying their "perfume" in an aroma lamp are a traditional remedy.
I crave oranges and chocolate in winter,
so perhaps I am a little affected too.
Oh, and physical activity helps as well.