In this study we plan two principal objectives. First, we will investigate the level of HIV expression in plasma samples at low viral loads using a new HIV load assay with enhanced sensitivity and precision in the viral load range of 1-100 copies. If data from the survey confirms acceptable performance characteristics for this assay we will proceed with stage II of the protocol. In stage II we plan to determine, in several short-term intensification approaches to investigate whether the incorporation of an additional antiretroviral to suppressive HAART regimens ("intensification HAART") will further suppress plasma virus. In a small pilot study, we will plan to intensify regimens for 30 days in a nonrandomized fashion. Secondly, we plan to study patients who are switching medications for preference or mild toxicity. In these patients we will intensify their regimens for 30 days in an overlap fashion, adding the new drug instead of switching medications. After 30 days of drug overlap, we will continue the new drug and discontinue the identified antiretroviral. These initial studies will assist in obtaining initial data and confirming the estimated sample size of a larger, randomized study to rigorously investigate the virologic effects of drug intensification. If these initial proof-of-concept experiments suggest that HIV may be suppressed by intensification HAART, then we plan to expand the study in a larger controlled trial to determine the degree of suppression possible with intensification therapy.