The Safety and Effectiveness of Nevirapine Plus Nelfinavir in HIV-1 Infected Patients Who Have Taken Stavudine

Inclusion Criteria Patients must have: * Documented HIV infection. * CD4+ cell count \>= 100 cells/mm3. * Plasma HIV-1 RNA \>= 5000 copies/ml. Prior Medication: Allowed: Previous antiretroviral therapy with zidovudine, lamivudine, didanosine, and dideoxycytidine. Exclusion Criteria Co-existing Condition: Patients with the following symptoms and conditions are excluded: * Malabsorption, severe chronic diarrhea, or the inability to maintain adequate oral intake. * Undergoing treatment for an active infection. * Hepatic insufficiency due to cirrhosis. * Renal insufficiency. 1\. Systemic treatment with corticosteroids or drugs known to be hepatic enzyme inducers or inhibitors within 14 days of entry. Substances in these categories include: * macrolide antibiotics (erythromycin, clarithromycin, azithromycin, dirithromycin), azole antifungals (ketoconazole, fluconazole, itraconazole), rifampin, rifabutin, and phenytoin. * Previous exposure to non-nucleoside reverse transcriptase inhibitors (NNRTIs) such as delavirdine, loviride, DMP 266, or nevirapine and/or protease inhibitors (PI) such as saquinavir, ritonavir, indinavir, and nelfinavir. * \> 6 months previous exposure to d4T. * Investigational drugs within 30 days of first dose of study medication. * Any antineoplastic agent within 12 weeks before starting study medication. Radiotherapy, other than local skin radiotherapy treatment, within 12 weeks prior to study. 1\. History of intravenous drug abuse or alcohol or substance abuse considered by the Investigator and BIPI Medical Monitor to be a significant impairment to health and compliance. * Heavy smokers (e.g., \> 20 cigarettes per day).