Patients receive a regimen of didanosine, stavudine, nevirapine, and MKC-442 for 24 weeks. Throughout the study, patients are evaluated for changes from baseline in plasma HIV-1 RNA levels and lymphocyte subsets and for development of adverse events and toxicities. Patients who experience virologic failure have the option of adding hydroxyurea to their treatment regimen or discontinuing from the study. After Week 24, patients with documented virologic response may continue treatment with didanosine, stavudine, nevirapine, and MKC-442, and, if applicable, hydroxyurea until a change in virologic status occurs (i.e., the patient experiences virologic failure). Follow-up visits are conducted every 4 to 12 weeks until permanent discontinuation from the study.