Patients accepted into the study are randomly assigned to FCZ or AMB. Patients assigned to FCZ take FCZ by mouth daily for 10 weeks. Patients assigned to AMB are given intravenous injections of AMB daily for 6-10 weeks. Non-AIDS patients assigned to AMB also take FLC by mouth daily. The use of FLC in patients with AIDS is decided on an individual basis. Patients with AIDS who respond satisfactorily to FCZ receive maintenance therapy to prevent relapse for an additional 12 months. Patients with AIDS who respond to AMB may qualify for another Pfizer Central Research protocol. Patients without AIDS who respond to therapy are observed for 6 months for relapse. During therapy, samples of blood and cerebrospinal fluid (by lumbar puncture) are taken periodically in order to evaluate the effectiveness of the drug treatments and to identify possible toxic effects.