Achieving viral suppression has been widely endorsed as the primary goal of HIV therapy, yet there are few established guidelines to provide the framework by which to devise combinations of different classes of drugs which will not only enhance the potential for achieving viral suppression while reducing the risk of toxicity but will also preserve therapeutic options for future use. This study includes 2 antiretroviral compounds, NFV (a protease inhibitor [PI]) and EFV (a nonnucleoside reverse transcriptase inhibitor [NNRTI]), for use either alone or in combination with reverse transcriptase inhibitor (RTI) therapy for the purpose of limiting HIV replication. [AS PER AMENDMENT 3/5/98: Patients who experience treatment failure at Week 16 or later choose 1 of the following alternative potent salvage therapy regimens: a dual-PI regimen (saquinavir/ritonavir) plus adefovir dipivoxil and L-carnitine; EFV or NFV (if not already given) plus 2 new approved antiretroviral drugs outside the study; or the best available treatment outside the study. The new reverse transcriptase inhibitor, adefovir dipivoxil, is added to the dual-PI regimen to achieve suppression of viral replication and thereby delay disease progression.]