 This is a 2-year study to examine the effects of a new experimental medication MK0822 on postmenopausal osteoporosis. This study will enroll approximately 375 postmenopausal women, and randomly assign them to 4 different doses of MK0822or to placebo. Measurements performed during the study include: bone mineral density scans, spine x-rays, laboratory blood and urine tests, height measurements and optional bone biopsies at the end of 2 years. 