This study proposes to investigate the use of combined ganciclovir and foscarnet to maximize the antiviral regimen. Current evidence suggests that a combination of ganciclovir and foscarnet may be the most efficacious therapy and appears to be well tolerated. This study will provide key information regarding safety and CSF penetration of the drugs available for treatment of these lethal diseases. It will also provide preliminary information regarding virologic factors relevant to CMV CNS disease. The study will also provide further data about the natural history of CMV brain infection detected by a combination of symptom complex and PCR identification of CMV in CSF and the potential of semi-quantitative PCR evaluation of the CSF for the disease.