[AS PER AMENDMENT 10/02/97: To compare by intention-to-treat analysis for disease progression, including death, the following two regimens: NFV plus background combination antiretroviral (AR) therapy followed by indinavir (IDV) or RTV in the event of significant intolerance; and RTV plus AR therapy followed by IDV, then NFV, in the event of significant intolerance.] [AS PER AMENDMENT 3/11/98: SUBSTUDY CPCRA 045: To determine the relative rates of emergence of HIV-1 resistance and to compare changes in plasma HIV RNA levels and CD4+ cell counts in a sample of patients with CD4+ cell counts <= 200/mm3 who are enrolled in protocol CPCRA 042.] AR therapy is rapidly becoming the standard of care for the treatment of HIV infection. AR therapy provides the best opportunity for maximizing viral suppression, reducing toxicity and delaying the emergence of resistant strains. The newest class of AR agents, the HIV protease inhibitors, exhibits the most potent anti-HIV effects described to date. This study will compare 2 protease inhibitors, NFV and RTV for efficacy and safety in a population with advanced HIV disease, who are taking various background nucleoside therapies.