An Open-Label Study to Evaluate the Efficacy and Safety of Amprenavir (141W94) and Abacavir Combination Therapy in Protease Inhibitor Experienced Subjects With HIV-1 Infection Who Are Failing Their Current Antiretroviral Treatment Regimen

Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Hepatic failure with elevated ALT and AST values. * Malabsorption syndrome or other gastrointestinal dysfunction which may interfere with drug absorption or render the patient unable to take oral medication. * Renal failure requiring dialysis. Concurrent Medication: Excluded: Patients currently participating in, or who would qualify for or have access to, an enrolling study of APV (ACTG 398 and ACTG 400). Patients with the following prior conditions are excluded: * Patients suffering from serious medical conditions such as diabetes, congestive heart failure, cardiomyopathy, or other cardiac dysfunction which, in the opinion of the investigator, would compromise the safety of the patient. * History of clinically relevant pancreatitis or hepatitis within the last 6 months. Prior Medication: Excluded: * Previous treatment with more than one HIV protease inhibitor. * ABC use for greater than 8 weeks prior to enrollment into this study. Risk Behavior: Excluded: Patients with current alcohol or illicit drug use which, in the opinion of the investigator, would interfere with the patient's ability to comply with the requirements of the study. Patients have: * HIV-1 infection. * CD4+ cell count less than or equal to 400 cells/mm3 and plasma HIV-1 RNA greater than or equal to 10,000 copies/ml at the first pre-entry assessment. * Evidence of failure on an antiretroviral treatment regimen containing a protease inhibitor. * Clinical evidence of failure in their current regimen and require antiretroviral therapy, and need APV plus ABC to induce viral load suppression.