A Randomized, Prospective Study of the Efficacy, Safety and Tolerability of Two Doses of GW433908Ritonavir Given With Abacavir/Lamivudine Fixed Dose Combination

Inclusion Criteria: * HIV-1 infection * Male or Female 18 years of age or older * Has plasma HIV-1 RNA (viral load) 1,000 or more copies/mL at screening * Subject is antiretroviral-naïve ( less than 7 days of prior therapy with any agent * Competency * Not pregnant and willing to use effective birth control if applicable. Exclusion Criteria: * Inability to comply due to pre-existing mental, physical, or substance abuse disorder or other reason. * Has active/acute CDC Clinical Category C event at screening. * Has history of inflammatory bowel disease, gastrointestinal malignancy, intestinal ischemia, malabsorption or other gastrointestinal dysfunction. * Females who are pregnant or breastfeeding. * Has a serious medical condition, such as diabetes, congestive heart failure, cardiomyopathy or other cardiac dysfunction, which in the opinion of the investigator would compromise the safety of the subject. * Has ongoing clinically relevant pancreatitis or clinically relevant hepatitis at screening. * Requires treatment with foscarnet, hydroxyurea or other agents with documented activity against HIV-1 in vitro within 28 days of study drug administration. * Has an acute laboratory abnormality at screening that, in the opinion of the investigator, should preclude the subject's participation in the study. Any Grade 4 laboratory result would exclude a subject from study participation. * Has required treatment with radiation therapy or cytotoxic chemotherapeutic agents within 28 days prior to screening, or has an anticipated need for such a treatment within the study period. * Requires treatment with immunomodulating agents (such as systemic corticosteroids, interleukins, vaccines, or interferons) within 28 days prior to screening or subject has received an HIV-1 immunotherapeutic vaccine within 90 days prior to screening. * Has a history of allergy to any of the study drugs or any excipients therein. * Is enrolled or plans to enroll in one or more investigational drug protocols, which may impact HIV RNA suppression. * Requiring treatment with pharmacological agents for diabetes, or elevated triglycerides/cholesterol. * Has an AST or ALT \>5 times the upper limit of normal (ULN). * Has an estimated creatinine clearance \<50 mL/min via the Cockcroft-Gault method * Subject requires treatment with any of the following medications within 28 days prior to study drug administration, or the anticipated need during the study: amiodarone, astemizole, bepridil, cisapride, dihydroergotamine, ergonovine, ergotamine, flecainide, halofantrine, lidocaine, lovastatin, methylergonovine, midazolam, pimozide, propafenone, quinidine, simvastatin, terfenadine, and triazolam, carbamazepine, dexamethasone, phenobarbital, phenytoin, primidone, rifampin, and St. John's Wort (hypericum perforatum)