 Patients in this substudy will have Brachial Artery Reactivity Tests BARTs, which are painless ultrasound tests of an artery in the lower arm. Brachial artery reactivity will be measured at entry and at 4 and 24 weeks after patients are randomized to one of three open-label drug regimens in ACTG A5142. Brachial artery reactivity in response to two vasoactive stimuli flow-mediated and nitroglycerin will be assessed by measuring brachial artery diameter and flow velocity. Blood will be drawn at Weeks 4 and 24 for insulin and lipid tests. Patients will fast and refrain from tobacco and caffeine use for at least 8 hours prior to each study visit. For the duration of the substudy, patients will be asked not to change the amount of fruits, juices, antioxidants, and tea that they consume. 