To compare the proportion of patients in the 2 zidovudine (ZDV)-containing arms who have a plasma HIV RNA concentration below the limit of detection (defined as 500 copies/ml or less) at Weeks 20 and 24 [AS PER AMENDMENT 8/24/98: HIV RNA concentration below the limit of detection is now defined as 200 copies/ml or less]. To compare the safety and tolerability of the different treatment regimens. To compare the decrease in plasma HIV-1 RNA and the change in CD4 count from baseline to the average of Weeks 20 and 24 [AS PER AMENDMENT 12/19/97: and to the average of Weeks 44 and 48; AS PER AMENDMENT 8/24/98: and the average of Weeks 88 and 96] in the 2 ZDV-containing arms. To study the emergence of resistance to ZDV, lamivudine (3TC), stavudine (d4T), delavirdine (DLV), and indinavir (IDV) in treated patients. To correlate the antiviral and immunologic activity and emergence of drug resistance with pharmacologic parameters of study drugs. To delineate the pharmacokinetic interactions of IDV and DLV. [AS PER AMENDMENT 12/19/97: To delineate the possible development of cellular resistance to nucleoside analogs and the consequences of switching nucleoside study drugs on intracellular phosphorylation.] To document rates and patterns of adherence over the course of the study, from day of randomization through 48 weeks. [AS PER AMENDMENT 8/24/98: To define long-term durability of the virologic activity of the different treatment regimens, as defined by the proportion of patients with plasma HIV-1 RNA levels that remains below the limit of detection. To define long-term tolerability of the different treatment regimens.] Although a change in reverse transcriptase (RT) inhibitors is recommended when adding or changing protease inhibitors in a treatment regimen, the choice of available RT inhibitors is often limited by prior exposure, toxicity, or pharmacologic interaction with the protease inhibitors. This study addresses the question of whether to continue 3TC or substitute the nonnucleoside reverse transcriptase inhibitor (NNRTI) DLV when adding IDV to therapy for patients previously treated with ddI or d4T plus 3TC who have greater than 500 copies/ml of plasma HIV-1 RNA. Although the activity of DLV as monotherapy or in combination with nucleoside reverse transcriptase inhibitors is of limited duration due to rapid emergence of resistance, it is possible that DLV will contribute significantly to the activity of 3-drug regimens that include a new RT inhibitor plus a protease inhibitor.