A Study to Compare The Ability of Different Anti-HIV Drugs to Decrease Viral Load After Nelfinavir (an Anti-HIV Drug)Treatment Failure

The purpose of this study is to determine the safety and effectiveness of combining several anti-HIV drugs in order to decrease plasma viral load (level of HIV in the blood) in HIV-positive patients who have failed nelfinavir (NFV) treatment. In order to determine the ability of a drug regimen to decrease viral load after drug treatment has failed, it is best to test a variety different of drug "cocktails" (drug regimens). The drug cocktails in this study include 2 new nucleoside reverse transcriptase inhibitors (NRTIs), efavirenz (an NNRTI, non-nucleoside reverse transcriptase inhibitor), and either 1 or 2 protease inhibitors. It is important to include multiple drugs from different groups in a drug cocktail since combinations containing fewer drugs are likely to fail.