 This study will look to see if there are changes in the blood cells that are associated with bone disease and sort out effects that are due to the HIV virus itself, the medications and see if faster aging occurs in the cells of HIV infected persons. Bone disease will be measured by a special X-ray called a DEXA scan. A DEXA scan is used by doctors to see if someone has normal bone mass for their age or if there is thinning of the bones. 