 Participants in this study will remain on their usual antiretroviral regimen; no changes may be made to that regimen for the first 4 weeks of the study. Upon study entry, participants will have intracellular pharmacokinetic studies. During Week 2, participants will start either Rebetron or PEG-Intron plus ribavirin therapy, will have intracellular pharmacokinetic studies, and will undergo liver biopsy. Additional intracellular pharmacokinetic studies will be performed at Weeks 12 and 24. Rebetron or PEG-Intron plus ribavirin will be given for 48 weeks. A second liver biopsy will be performed 24 weeks after discontinuing Rebetron or PEG-Intron plus ribavirin therapy. Participants will be followed for 72 weeks. 