It won't be possible to have very strong joints without some muscles to back them up. The muscles and connective tissues that surround joints provide support, stability and guidance through the range of motion. You won't have to lift a Volkswagen on Muscle Beach for your joints to reap the benefits of muscle gain.
When you engage in weight-bearing exercises, your bones rise to the challenge and grow stronger in anticipation of supporting those loads again. Thicker bones equal fewer joint problems down the road.
Toning up will also improve your balance, meaning your joints will be less likely to sustain trauma in a nasty fall. Gaining muscle will also help you lose weight, which your joints will definitely appreciate -- your body continues burning higher rates of calories for hours after your workout.
You don't want to jump in carelessly, of course -- lifting weights the wrong way is worse than not doing it at all. Seek out the advice and guidance of a personal trainer to show you how to properly perform exercises that will build the muscle you need to protect your joints.