Safety and Effectiveness of Lamivudine When Given Once a Day Versus Twice a Day in Combination With Other Anti-HIV Drugs in HIV-Infected Adults Who Have Never Received Anti-HIV Drugs

Inclusion Criteria Patients may be eligible for this study if they: * Are 18 years of age or older. * Are HIV-positive. * Have a viral load (level of HIV in the blood) of at least 400 copies/ml within 21 days of study entry. * Have a CD4 count greater than 100 cells/mm3 within 21 days of study entry. * Agree to practice abstinence or use effective barrier methods of birth control (or, if patient is a woman, unable to have children). Exclusion Criteria Patients will not be eligible for this study if they: * Have taken any antiretroviral (anti-HIV) agent. * Are pregnant or breast-feeding. * Are unable to absorb food or have trouble taking medicines by mouth. * Abuse alcohol or drugs to an extent that may make study participation difficult. * Are not likely to be able to complete the 48 weeks of study treatment. * Have a history of pancreatitis (inflamed pancreas) or hepatitis within the last 6 months or any evidence of liver disease. * Have received an investigational vaccine within the past 3 months or have received gene therapy. * Have a severe medical condition such as diabetes or heart trouble. * Have been diagnosed with AIDS. * Have had radiation therapy or chemotherapy within 30 days of study entry, except for treatment of Kaposi's sarcoma. * Are taking medications that affect the immune system within 30 days of study entry. * Are taking medications that may interact with the study drugs.