The purpose of this study is to compare the safety and effectiveness of emtricitabine and stavudine when given with didanosine plus efavirenz to HIV-infected patients.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are at least 18 years old at the time of screening.
• Have plasma HIV-1 RNA loads (level of HIV in your blood) of 5,000 or more copies/ml at the time of screening.
• Have not used any anti-HIV therapy for more than 2 days.
• Have a negative pregnancy test within 22 days of starting study drugs.
• Can be reached by telephone.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Are pregnant or breast-feeding.
• Use alcohol or illegal drugs that, in the opinion of the principal investigator, may interfere with the patient's ability to follow the dosing schedule and protocol evaluations.
• Are being treated for active tuberculosis.
• Are using astemizole, cisapride, midazolam, triazolam, ergot derivatives, St. John's wort, or drugs for a mental disorder.
• Have a history of a serious mental disorder.
• Are unwilling to use an effective barrier method of birth control during the study (for women who can get pregnant).
• Have a history of opportunistic infections and cancers (Mycobacterium avium complex, cytomegalovirus, toxoplasmic encephalitis or disseminated toxoplasmosis, cryptosporidiosis, Isospora belli, progressive multifocal leukoencephalopathy, visceral Kaposi's sarcoma, and lymphoma). Patients with past episode of pulmonary tuberculosis, Pneumocystis carinii pneumonia, or isolated cutaneous Kaposi's sarcoma are allowed. Medication for the prevention of PCP (TMP/SMX, nebulized pentamidine, and atovaquone) is allowed.
• Have peripheral neuropathy (a painful condition affecting the nervous system) or history of peripheral neuropathy.
• Cannot take medicine by mouth or have severe chronic diarrhea within 30 days before beginning the study.
• Cannot eat 1 or more meals a day because of chronic nausea, vomiting, or abdominal or esophageal discomfort.
• Have had a serious illness or injury within 30 days of screening. Treatment must have been completed for 14 days prior to study entry.
• Have a history of AIDS-defining opportunistic infection, except for tuberculosis or infection of the stomach or intestines.