A Study to Evaluate the Long-Term Effectiveness of Three Anti-HIV Drug Regimens in HIV Infected Patients Who Have Never Been Exposed to Highly Active Antiretroviral Therapy (HAART)

Highly active antiretroviral therapy (HAART) regimens containing PIs, NNRTIs, or nucleoside reverse transcriptase inhibitors (NRTIs) have been shown to slow disease progression. However, the long-term consequences of initial therapy with a PI, an NNRTI, or both a PI and an NNRTI are not yet known, nor is the impact on future anti-HIV treatment regimens. Patients who experience virologic failure on a particular HAART regimen typically have not been studied for subsequent response to other HAART regimens. It is possible that a regimen which is initially the most potent may not be optimal if it limits the effectiveness of subsequent anti-HIV treatment regimens. Patients will be randomized to one of three HAART treatment arms: * Arm 1 participants will receive one or two PIs plus two NRTIs. * Arm 2 participants will receive one NNRTI plus two NRTIs. * Arm 3 participants will receive one or two PIs plus an NNRTI plus one or two NRTIs. Before randomization to a treatment arm, patients will be given the option of preselecting the drugs they will use or allowing randomization to study-specified drugs. The study-specified PIs will be indinavir (IDV), nelfinavir (NFV), or two PIs of patient and doctor choice. The study-specified NNRTIs will be nevirapine (NVP) or efavirenz (EFV). The study-specified NRTIs will be abacavir (ABC) plus lamivudine (3TC) or didanosine (ddI) plus stavudine (d4T). The study sites will provide ABC, 3TC, ddI, or d4T to all patients who are assigned to take these medications. All other anti-HIV drugs for initial and subsequent treatment regimens are obtained by clinician prescription. At Months 1 and 4 and then every 4 months thereafter, patients will receive a medical history update, physical exam, and questionnaire. Blood samples will also be drawn to measure CD4 cell count, viral load, and genotypic antiretroviral resistance. Changes in treatment regimens may occur at any time.