Spending long hours at the computer can cause muscle aches and, as you've learned, can adversely affect posture. My first recommendation is to make sure that your computer station is set up correctly in order to minimize any strain on your back, neck and arms. I suggest taking a look at this postural guide from the University of California at Los Angeles and making an effort to ensure that you follow the advice as closely as possible. I also urge you to be mindful of your posture since awareness is the major factor in maintaining correct posture.
I discussed your question about wearing a back brace to correct your posture with Theresa Cisler, D.O., an osteopath who practices in Tucson. She said that she wouldn't recommend using a brace because it would weaken muscles rather than improve your posture. Instead, she advised exercise as the best approach and rather than advocating any specific type of exercise, she suggests doing whatever type of activity you enjoy and can commit to on a regular basis. She also advised taking stretch breaks from the computer periodically and performing the stretches described in the chapter on exercise in Dr. Robert Fulford's book Dr. Fulford's Touch of Life. I second that recommendation. I studied with Dr. Fulford, a leading practitioner of cranial osteopathy, in the 1970s and still consider him the most effective clinician and healer I've ever known.
Another expert, Harmon Myers, D.O., a member of the faculty of the Arizona Center for Integrative Medicine, noted that a back brace or other type of support "by its very nature limits the motion of certain muscles, which over a long term weakens an area. Postural problems usually require exercises and evaluation of the patient's workplace by an occupational therapist."
You also may want to consider the Feldenkrais Method to improve your posture. Named after its originator, Dr. Moshe Feldenkrais, D.Sc. (1904-1984), a Russian-born physicist, judo expert, mechanical engineer and educator, the Feldenkrais Method is based on the principles of physics and biomechanics, an empirical understanding of human physiology, and the connection between mind and body. It can correct poor posture and habits of movement that may be causing pain. To find a qualified practitioner in your area go to www.feldenkrais.com.
Andrew Weil, M.D.