All patients will be enrolled within the first 18 months of the study. They will be randomized to 1 of 2 groups. Group 1 will be comprised of 1080 patients and will receive adefovir dipivoxil plus L-carnitine and group 2 will be comprised of 1080 patients and will receive a placebo plus L-carnitine. At least the first 400 patients enrolled (200 in each group) will comprise the safety-HIV virology cohort. These patients will have more frequent follow up visits, additional laboratory evaluations, and more intensive safety data information during the first 6 months. NOTE: At least 850 patients who are infected with CMV are followed for the development of CMV end-organ disease in a CMV prophylaxis substudy.