A Study of the Safety and Effectiveness of Combination Anti-HIV Therapy in HIV-Infected Adults

Inclusion Criteria Patients may be eligible for this study if they: * Are HIV-positive. * Have HIV levels of 50,000 copies/ml or more within 21 days prior to starting treatment. * Are at least 18 years of age. * Are willing to use an effective method of birth control during the study. * (This study has been changed. A CD4 cell count of 50/mm3 or more within 21 days prior to starting treatment is no longer required.) Exclusion Criteria Patients will not be eligible for this study if they: * Are pregnant. * Have AIDS. * Cannot take medications by mouth. * Have hepatitis and it is active. * Are enrolled in other investigational drug studies. * Are allergic to any of the study drugs. * Have a serious medical condition, such as heart disease. * Have ever taken certain anti-HIV drugs such as nonnucleoside reverse transcriptase inhibitors (NNRTIs) or protease inhibitors (PIs). * Have ever had more than 7 days of treatment with a nucleoside reverse transcriptase inhibitor (NRTI). Patients should have no prior treatment with abacavir and no prior treatment with at least one of the following: lamivudine or zidovudine. * Have had radiation therapy or chemotherapy within 4 weeks prior to study entry, or plan to have such therapy during the study. * Have received medications that might affect the immune system, such as systemic corticosteroids, interleukins, vaccines, or interferons within 4 weeks prior to study entry. * Have received an HIV vaccine within 3 months prior to study entry. * Are taking foscarnet, hydroxyurea, or other drugs that work against HIV. * Have taken certain medications such as astemizole, cisapride, dihydroergotamine, ergotamine, ganciclovir, interferon-alpha, midazolam, terfenadine, and triazolam within 21 days of study entry. * Abuse alcohol or drugs. * Are unable to complete the whole study.