The purpose of this study is to evaluate the non-inferiority of ritonavir-boosted GS-9137 relative to a ritonavir-boosted Comparator Protease Inhibitor when used as part of combination antiretroviral regimens in subjects who have failed, or are failing, protease inhibitor therapy.

Inclusion Criteria:

• HIV RNA greater than or equal to 1000 c/mL.
• Failed/Failing protease inhibitor based antiretroviral therapy.
• Stable antiretroviral therapy for greater than or equal to 30 days prior to screening.
• Negative Serum Pregnancy Test.
• GFR by Cockcroft Gault greater than or equal to 80 mL/min.
• AST & ALT less than or equal to 2.5x ULN.
• Total Bilirubin less than or equal to 1.5 mg/dL.
• Albumin greater than 3.5 mg/dL.
• Prothrombin Time INR 1.0-1.4
• Platelets greater than or equal to 50,000.
• Hemoglobin greater than or equal to 8.0 mg/dL.
• Absolute Neutrophil Count greater than or equal to 1000.

Exclusion Criteria:

• New AIDS defining condition within 30 days of baseline.
• Prior treatment with HIV-1 integrase inhibitor (except patients from 183-101).
• Ascites or encephalopathy.
• Breast Feeding.
• Cancer Diagnosis (besides Kaposi Sarcoma or Basal Cell Carcinoma).