Patients will be randomly assigned to one of three study arms. Arms A, B, and C receive the same daily dosage of lopinavir/ritonavir (LPV/r), emtricitabine (FTC), and stavudine extended release (d4T XR) or tenofovir DF (TDF). In Arm A, drugs are self-administered for 48 weeks; LPV/r is taken twice daily and FTC and d4T XR or TDF once daily. In Arm B, all drugs are self-administered once daily for 48 weeks. In Arm C, drugs are taken once a day under directly observed therapy during Weeks 0-24, and then by self-administration during Weeks 25-48. Adherence to the regimen is measured using an electronic drug monitoring system. Viral load, CD4 and CD8 T cell responses, population pharmacokinetics, and quality of life indicators are measured throughout the study. The tolerability and safety of the treatment regimens are also monitored.