To evaluate the durability of virologic response as assessed by the Roche Ultra Sensitive assay (< 200 copies/ml) and culturable virus. To compare time to a confirmed virologic response (two consecutive plasma HIV RNA levels < 500 copies/ml) or to a confirmed treatment relapse following a confirmed virologic response across the treatment arms. To evaluate biologic phenotype (non-syncytium inducing versus syncytium inducing capacity) and the evolution and patterns of viral resistance among patients with confirmed treatment failures at or after weeks 16 to 24. To compare immunologic benefits, as measured by longitudinal CD4/CD8 cell count profiles. To evaluate the influence of baseline virologic and immunologic parameters on the magnitude and duration of plasma HIV RNA response. To compare virologic response between the two dose schedules of NFV and SQVsgc (bid vs tid) and between NFV and SQVsgc with either DLV or combination 3TC/ZDV. To evaluate compliance and exploratory population pharmacometrics.