Treatment with HIV-infection with protease inhibitors is associated with high blood lipids and higher chance for cardiovascular complications. The RASSTER study aims to investigate the effect of switching the protease inhibitor lopinavir/ritonavir to raltegravir on vessel wall function and inflammation,and activation of the immune system. we hypothesize that with this intervention these parameters will improve. Since decreased vessel wall function and inflammation are initial steps in the process of atherosclerosis, it is important to know this data when treating HIV-infected patients.