In this double-blind, double-placebo, randomized, 2-arm study, atazanavir and NFV each are given in combination with 2 open-label nucleoside reverse transcriptase inhibitors (NRTIs) over 48 weeks. Patients assigned to atazanavir will receive placebo capsules which are identical in size and appearance to NFV. Patients assigned to NFV will receive placebo capsules which are identical in size and appearance to atazanavir. HIV levels are monitored.