A Phase IV 48-Week, Randomized, Open-Label, Multicenter Trial of Abacavir (300mg BID)/Efavirenz (600mg QD)/Didanosine (400mg QD) +/- Hydroxyurea (500mg BID) in HIV-1 Infected Subjects Failing Initial Therapy With 3TC/ZDV (or d4T) +/- Protease Inhibitor(s)

Patients are randomized into one of two treatment arms: ABC/EFV/ddI or ABC/EFV/ddI/HU. In the second treatment arm, patients are further randomized to receive HU beginning at Baseline, when ABC/EFV/ddI is started, or at Week 8. Delaying HU may help offset the cytopenic effect of HU, as reflected in a blunted CD4 cell response. Patients are stratified according to their screening plasma HIV-1 RNA level (400 to 10,000 copies/ml and more than 10,000 to 100,000 copies/ml). Participants in the study receive study-related exams, lab tests, and study medications at no cost over the 48-week treatment period. The safety and effectiveness of the non-protease inhibitor rescue therapy is evaluated routinely by measuring viral load and the CD4 cell count, as well as the side effects caused by the medications. All of the medications are approved by the FDA and are not considered investigational.