To compare the proportion of patients who achieve plasma HIV-1 RNA concentrations below 500 copies/ml, as assessed by the standard Roche Amplicor assay at Week 16, or to compare the absolute changes in plasma HIV-1 RNA concentrations at Week 16 across the treatment arms: ABC or approved nucleoside analogs and nelfinavir (NFV) or placebo in combination with efavirenz (EFV) and adefovir dipivoxil. To compare the safety and tolerability of these treatment arms.