Anti-HIV drug therapy using PIs has become very common treatment for HIV-positive patients. Recently, however, serious side effects involving how the body uses fat are being reported in patients taking PIs. Examples of these side effects are a redistribution of body fat, high cholesterol level, and development of diabetes. However, some of these side effects have also been seen in patients who are not taking PIs. It is important to determine whether or not these side effects are directly related to PI use. In this study, patients on different drug combinations, either with or without a PI, will be compared.