The purpose of this study is to assess differences in changes in plasma lipids between patients on saquinavir/ritonavir or atazanavir/ritonavir in combination with tenofovir disoproxil fumarate and emtricitabine as a first-line regimen in patients previously naive for antiretroviral therapy. This study is an extension from the SSAR 2004/0002 which randomised patients over the same treatment arms.