This study will be conducted in HIV+, multiple ARV medication experienced patients. All patients must have received treatment from each of three ARV classes: NRTIs, NNRTIs and PIs, have received at least two PI-based ARV regimens (may include the current regimen) with a viral load greater than or equal to 1000 copies/mL at the time of study entry. The two separate PI-based regimens must each have been taken for at least 3 months. At least one resistance-conferring PI-mutation (from a pre-established panel) must be present. Baseline genotypic screening will be performed and will be used in conjunction with ARV medication history to determine new background therapy for each individual subject to use.