This study is being done with people who are infected with HIV and need to start treatment for their HIV disease. The purpose of this study is to see if taking vitamin D and calcium will help prevent the bone loss that sometimes happens when people start HIV treatment. For this study, the following HIV treatment (or HAART) will be provided in the form of a single tablet that contains three different drugs: efavirenz/emtricitabine/tenofovir (EFV/FTC/TDF). These drugs are approved by the FDA to treat HIV infection. The HIV treatment provided is common for people who are taking HIV drugs for the first time. The risks seen with this HIV treatment are the same that you would encounter when taking these drugs outside of the study. The lists of risks of this HIV treatment are included in this document because the drugs are provided by the study, not because the drugs are being tested. The purpose of the study is only to look at the impact of high doses of vitamin D and calcium in preventing bone loss; the HIV treatment is not being tested.