The purpose of this study is to compare the effectiveness of various combinations of anti-HIV drugs in HIV-positive men and women. Patients receive specific combinations of 3 or 4 of the following 6 drugs: didanosine (ddI), stavudine (d4T) efavirenz (EFV), nelfinavir (NFV), lamivudine (3TC), or zidovudine (ZDV).