The primary hypothesis of this study is that BMC and BMD will increase in HIV-infected subjects randomized to receive vitamin D3 plus calcium compared to subjects receiving placebo. We will test this hypothesis by comparing TBBMC, TBBMD, SBMC, and SBMD measured by total body and spine DXA scans performed at baseline and at 1 and 2 years post-randomization in the 2 study arms using an intention-to-treat analysis.