This study will compare the ability of fosamprenavir 700 mg with ritonavir 100 mg twice a day or lopinavir 400 mg with ritonavir 100 mg twice a day both combined with a fixed dose combination tablet of abacavir 600 mg and lamivudine 300 mg once a day to suppress virus levels of HIV to less than 400 copies/mL of blood. In addition we will study the safety and tolerability of these compounds over the 48 week study period in patients naive to anti-HIV therapy.

A Phase IIIB, Randomized, Open-Label, Multicenter Study of the Safety and Efficacy of GW433908 (700mg BID) plus ritonavir (100mg BID) Versus Lopinavir/ritonavir (400mg/100mg BID) when Administered in Combination with the Abacavir/Lamivudine (600mg/300mg) Fixed-Dose Combination Tablet QD in Antiretroviral-Naive HIV-1 Infected Adults Over 48 Weeks

Inclusion Criteria:

• HIV infected subjects that are naive to anti-HIV therapy.
• History of a positive HIV test.
• At least 1000 copies/mL of HIV in their blood as screening.

Exclusion Criteria:

• Active HIV-related diseases.
• Taking other investigational drugs.
• Pregnant or breastfeeding females.
• Not be suitable to participate per investigator opinion.