HBV presents a worldwide health crisis and is difficult to treat when a patient's HBV strain is no longer responsive to 3TC. Given the significant incidence of 3TC-resistant HBV in patients receiving this drug as part of an antiretroviral regimen, other agents with anti-HBV activity are needed. ADV has shown promising anti-HBV activity in preclinical assessments and in Phase I, II, and III clinical trials. TDF, developed for the treatment of HIV infection, has in vitro activity against HBV. This study will compare TDF/3TC combination therapy with ADV/3TC combination therapy to determine which treatment regimen is more effective in patients coinfected with HBV and HIV.