After unblinding, patients who were not receiving MMF may add it to their antiretroviral regimen. Response to the addition of open-label MMF is assessed after 2 weeks. Resistance to antiretroviral agents, including DAPD, will be assessed following any virologic failure occurring after Week 2. All patients have the option of optimizing their background antiretroviral regimen at Week 2, based on the results of a pre-entry resistance assay; enfuvirtide will be made available for background therapy optimization through Week 48.