I thought the turkeys already come brined?
Here is Alice Waters brine recipe... We found that the meat was too salty if you soaked a 18# bird for more than 8 hours.
http://www.globalgourmet.com/food/special/2000/secrets/brine.html
Most of them do; the package will tell you by saying it contains up to an X% of a saline solution. Regardless, I always brine them. I take one of those big beer coolers and use 1 cup each of salt and brown sugar to a gallon of water. I like to add some citrus to it also. This not only makes it moist but flavors it as well.
My wife and I were watching Emeril Live last night and she said it was like watching me make a turkey. I've always done what he does, but I use lemons instead of oranges. I might try oranges this year, because that sounded intriguing.
I agree with GRRRRR about garlic and turkey. I used to use it but havent in the past few years, and I haven't missed it. If you must, I would just add a few cloves into the cavity just to get a mild roasted garlic flavor.