What might ease a few of your aches and pains even more than a new pair of shoes is a pair of compression tights. They don't come cheap, but I can almost guarantee they'll make you feel better.
Opedix's R1 tight ($190; opedix.com) uses what they call an "anchor and sling" system to keep your joints aligned throughout your entire running range of motion (or skiing or cycling or whatever sport you choose). That helps reduce the pressure on your knees and almost instantly provides pain relief. Even your mild arthritis might ease up because you'll be "unloading" the joint, reducing wear and tear on the interior of your knee. The R1 may be a little too hot for the summer, but come fall, winter, and spring, you'll live in them.
For summer, try CW-X's Stabilyx tight ($86; cw-x.com). CW-X uses a similar webbed system to band your muscles and ligaments more tightly together, which stabilizes your knee, harnesses your midsection, supports your abs, hips, and back, and generally puts you in a more proper running/cycling position, which will only make you feel fitter, faster, and stronger.