This study tests a new form of didanosine, ddI EC, a coated pill that passes through the stomach before dissolving. The purpose of this study is to compare the effectiveness of an anti-HIV drug combination that includes ddI EC versus another anti-HIV drug combination.

Patients are randomized to 1 of 2 groups for 48 weeks of open-label treatment. Group 1 receives ddI EC plus d4T plus NFV. Group 2 receives Combivir plus NFV. Antiviral activity is determined by the proportion of patients with HIV RNA levels of less than 400 copies/ml at Week 48.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have a viral load of at least 2,000 copies/ml and a CD4 count of at least 200 cells/mm3.
• Are at least 18 years old.
• Agree to practice sexual abstinence or to use effective barrier methods of birth control (such as condoms).

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have had severe diarrhea within 30 days of study entry.
• Have a history of pancreatic disease or any other serious condition.
• Have hepatitis within 30 days of study entry.
• Are diagnosed with an opportunistic (AIDS-related) infection at the time of enrollment.
• Are unable to take medications by mouth.
• Have received certain medications.
• Are pregnant or breast-feeding.