Participants in this study had a CD4 cell count and viral load test during a screening visit. Participants had an entry visit that included blood and urine tests. Participants were then randomly assigned to one of four groups: Groups PI/1K and PI/30K received two NRTIs plus a PI; Groups NNRTI/1K and NNRTI/30K received two NRTIs plus an NNRTI. The medications allowed in the study were: abacavir, didanosine, emtricitabine, emtricitabine/tenofovir disoproxil fumarate, lamivudine, lamivudine/zidovudine, stavudine, tenofovir disoproxil fumarate, zalcitabine, and zidovudine (NRTIs); efavirenz and nevirapine (NNRTIs); efavirenz/emtricitabine/tenofovir disoproxil fumurate (NNRTI/NRTI); and amprenavir,atazanavir, darunavir, fosamprenavir calcium, indinavir, lopinavir/ritonavir, nelfinavir, saquinavir, ritonavir, and tipranavir (PIs). Note: Per the 06/28/05 amendment of this trial, emtricitabine, emtricitabine/tenofovir disoproxil fumarate, and tenofovir dioproxil fumarate were added to the list of medications that could be included in a participant's treatment regimen.