The hypothesis for this study is will a treatment regimen containing Atazanavir in combination with Ritonavir work as well as other regimens containing a protease inhibitor (PI, one of 5 classes of HIV Medications) and/or a Non-nucleoside Reverse Transcriptase Inhibitor (NNRTI, another of the classes of HIV medications) at controlling HIV disease in children who are HIV+ and have high cholesterol or high triglycerides. . In this study, children who have high cholesterol or high triglycerides as a result of their HIV medicines, will have the PI or NNRTI in their medication regimen changed to Atazanavir, which is a PI in combination with a low dose of Ritonavir (another PI). Atazanavir has been shown in adults to result in lower cholesterol and triglycerides than other PI's and NNRTI's. The dose of atazanavir and ritonavir will be according to the Package Insert for this drug that is FDA approved for children. They will continue taking the other medications from the pre-study regimen. Children will take study drug for 24 weeks, and will be able to continue study drug after the study using commercially available drug. Lab tests and a physical exam will be undertaken at 4 weeks, 12 weeks and 24 weeks after starting study drug to determine how effective the new drug is and to monitor for possible side effects.