AS PER AMENDMENT 10/20/97: For PRAM-1, Step 2: Interim analysis at 12 weeks on PRAM-1 indicates that the proportion of children reaching undetectable RNA levels on the ZDV + 3TC arm is significantly less than the other two arms. The protocol, therefore, has been modified (Step 2) to permit children in the ZDV + 3TC arm with RNA copy number >= 10,000 the opportunity to change to a novel therapeutic regimen (d4T + nevirapine + ritonavir).