Neuropathy results from damage to the nerves in the feet and legs. It is usually experienced as pain, tingling or numbness. In HIV-infected people, neuropathy can result from the infection itself or be a side effect of antiretroviral treatment. The purpose of this study is to determine whether two different drugs, methadone and duloxetine, reduce neuropathy-associated pain in HIV-infected people. This study will also examine whether utilization of both of these drugs is more effective than treatment with only one.