To determine whether cidofovir therapy can extend the time to progression of peripheral CMV retinitis; to evaluate the safety and tolerance of cidofovir therapy in AIDS patients with CMV retinitis when administered by intravenous infusion; to evaluate the virologic effects of cidofovir therapy on CMV sheeding in urine, blood, and/or semen when administered by intravenous infusion and to evaluate the effects of cidofovir therapy on the development of biopsy documented extraocular CMV disease when administered by intravenous infusion.