to give you a little background....
....MSM is widely available at feed stores. in the past, race horses put out to pasture/stud quite often had joint problems. Somehow it was discovered that giving a race horse MSM will reduce their arthritic joint pain. From an observational standpoint, the horses bbecome friskey again, and will romp and play in the fields, where they had not been doing so previously. in fact, many experienced horse owners use MSM on their older horses. It is extremely inexpensive.
....msm is a sulphuric based compound and stands for Methylsulfonylmethane. It promotes collegen synthesis, and I believe is a mild anti inflamatory.
....I take somewhere between 5 and 10 grams a day, and have been doing so for over 15 years. Because it improves collegen synthesis, one of the sides, claimed by many, is a more robust, natural growing finger/toe nail. This means you need to clip them more frequently.
You can also read abouut it on wiki here:
http://en.wikipedia.org/wiki/Methylsulfonylmethane
Let me know if any other questions
---Roman