Any great exercises i can do that will not put too much pressure on my knees w/ arthritis? they ache at times.

Straight leg raises: Lay down on your back with your legs straight out. Lift one leg at a time, keeping your knee straight. Repeat several times until fatigued. Then perform with the other leg. When you get stronger , you can add weight(fill an old purse with cans of food or water bottles, and hang the purse from your ankle). Apply ice to your knees for 10-20 minutes when you are finished.