Patients are randomized to receive blinded stavudine extended release (d4T ER) or immediate release (d4T IR) formulation. Randomization is balanced by screening HIV viral load of less than 30,000 copies/ml or at least 30,000 copies/ml and by site. Patients also receive open-label efavirenz (EFV) and lamivudine (3TC). Efficacy is evaluated over 48 weeks of the dosing period and safety is evaluated over the entire dosing period (56 weeks).