Knee aches

I've had problem knees for quite some time, but I've never seen a doctor for it.  I just assume it's a little arthritis, probably exacerbated by my weight.  They pop a lot when I stand up from a seated position, and sometimes coming down stairs.  They've started to ache a little bit more, probably due to my increased exercise load.  I hate the thought of incurring an injury that might sideline my exercise at this point, because I've finally gotten to a point where I really look forward to it, and make it a priority.  I'm wondering whether I should see a doc, or maybe at least try some supplements.  I read an article in prevention that mentioned using Sam-E and a combination of Glucosamine & Chondroitin (like Osteo Biflex).  Has anyone used either of those?  I'm doing spinning now, which is very low impact, and a good lower body toning workout.  But, should I still do my lower body strength (Cybex) workout as well?  I can feel it in my knees, especially when I do the leg extensions.   Any advice would be greatly appreciated! Tami

I would definately see a doctor.  I have a knee injury from a fall at work but before never had popping just like a grinding noise due to weight and a little bit of arthritis.  But the popping is a bad sign, not trying to scare you but take care of it because it could give out on you. Take care. ~D