Chondroitin Sulfate

glucosamine/chondroitin--does it work as a preventative?
I'm 31, a natural healing junkie. I've got sore knees from a lifetime of playing tennis. I've got some carpal tunnel from typing/restaurant work. I've always been interested in gluc/chond supplements but reluctant to pay the big bucks for them. walgreens has some on sale buy one get one free and i'm tempted. will they be beneficial to a mostly healthy non-arthritis sufferer? does just glucosamine work or do i need to get the mixed formula? any tips about what to watch out for when buying--standardized etc? gluc sulfate versus other formulas?
I was told by my pharmacist (he's great, if he is not sure about anything, he'll do the research to find out for me) that glucosimine with sulfate is the one my husband should take. Together, they repair and maintain joint and surrounding tissues. The added supplements in other glucosimine formulas are very little amounts of pain medications, that, in his opinion is not enough to deal with the pain and lessens the amount of glucosimine, which is the good stuff. He said the sulfate enhances the glucosimine abilities. My hubby had very bad shoulders & his knees, ankles, wrists were acting up.He could not raise his arms above his shoulders, bend his knees well, etc. He has been taking it for 2 years now, 1 in the morn. & 1 in the eve., and it helps him immeasureably. He was told it may take 1-2 months to see measureable results; it is, after all, repairing damage and that takes time, as I'm sure you know. We recommend it highly.