Guidelines have continued to list lopinavir/ritonavir as a preferred protease inhibitor-containing regimen for HIV-infected individuals. There has recently been increasing interest in once daily therapy. While lopinavir/ritonavir has recently been approved as a once daily therapy it was associated with considerable diarrhea in those treated with soft gel capsules. It is the hope that alternative formulations of lopinavir/ritonavir may provide similar pharmacokinetics with improved tolerability. This includes the possibility of using liquid or newly released tablets. This study will treat people tolerating their current regimen with up to four weeks of each formulation with several assessments of pharmacokinetics and tolerability for each.