This study allows patients who have successfully participated in ACTG 347 or other trials involving amprenavir to continue treatment with amprenavir, ZDV, d4T, and 3TC. Additionally, this study provides patients whose HIV-1 RNA was not reduced to undetectable levels or who had a significant increase in plasma levels ("treatment failures") the opportunity to change to a potentially more active regimen that includes indinavir, nevirapine, lamivudine, and stavudine.