Visiting the Louvre in Winter 2012?

We are going to Paris in the middle to end of January 2012, and we definitely intend on spending a day at the Louvre. Do you have to line up? Is this because they only let a certain amount of people in at a time or is it just because it takes so long to get tickets (do you even need to buy tickets?) that lines build up? How long do these lines take? Or will there be less lines because it is winter when we are there. Is there any time (like early in the morning) we can go to get away from the crowds? Thank you for your help!