A Study to Compare Two Anti-HIV Drug Combinations That Include Amprenavir in HIV-Infected Patients Who Have Failed Anti-HIV Drug Combinations That Did Not Include Amprenavir

Inclusion Criteria You may be eligible for this trial if you: Are HIV-positive. Are 13 years of age or older. Are currently taking anti-HIV drugs, 1 of which must be NFV or IDV, and have taken these same drugs for at least 12 weeks. In the last 16 weeks your viral load (level of HIV in the blood) dropped below 400 copies/ml and has since increased to at least 1,000 copies/ml, even though you continue to take your anti-HIV drugs. Have the written consent of a parent or legal guardian if you are under age 18. Agree to practice abstinence or use effective barrier methods of birth control (unless you are physically incapable of becoming pregnant). Are willing to complete the 48-week study. Exclusion Criteria You will not be eligible for this trial if you: Have ever taken the following anti-HIV drugs: ABC, APV, efavirenz (EFV), delavirdine (DLV), nevirapine (NVP), or loviride. Have certain AIDS-related infections or diseases, have other serious medical conditions such as diabetes and certain types of heart trouble, or have a history of lymphoma. Have had certain types of hepatitis in the past 6 months. Have received an HIV vaccine in the past 3 months or a flu vaccine in the past 30 days. Have certain digestion problems that make it difficult to take anti-HIV drugs by mouth. Have received certain other drugs or treatments in the past 30 days, or will need certain drugs or treatments during the study.