Patients will be seen in clinic for 6 days when treatment begins to measure blood levels of the medicines and evaluate the response of the virus. Treatment will then continue on an outpatient basis. Drug levels will be measured periodically throughout the study. The viral load will also be measured and additional tests to determine whether the resistance pattern of the patients' virus has changed. In addition, patients will undergo the following tests and procedures at various times throughout the study, more frequently for the first few months and then less often: