People wanting to explore a bit before finding a teacher might also like to check out www.alexandercenter.org and try the brief exercises described in "At Your Desk" and "Breathing," by the same Alexander teacher who wrote "Notes on a First Lesson" (referenced above in Mark Clark's link to Alexander Technique.com). The author, Leland Vall, is a friend of mine so I have a bias, but I find "At Your Desk" very useful and fun and have recommended it to other people who have also found it beneficial.
Margaret