Patients are enrolled into 1 of 4 study arms based on their current oral ARV regimens. Arm A takes NFV plus nucleoside reverse transcriptase inhibitors (NRTIs). Arm B takes LPV/r plus NRTIs. Arm C takes EFV plus NRTIs. Arm D enrolls HIV-infected patients not on current ARVs, or who are taking NRTIs only (no protease inhibitors [PIs] or nonnucleoside reverse transcriptase inhibitors [NNRTIs]). All arms receive HRT with oral estradiol and medroxyprogesterone acetate for 12 weeks. Arms A, B, and C have intensive PI or NNRTI pharmacokinetic (PK) sampling at entry and Week 4. All arms have estradiol PK sampling at Week 4. Clinical and laboratory evaluations are done at entry, Week 4, and Week 12.