The present invention concerns sulfonamide derivatives having the general formula and N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs and esters thereof, wherein Q1 is —S— or —O—; R1 is hydrogen, C1-6alkyl, hydroxy, amino, halogen, aminoC1-4alkyl and mono- or di(C1-4alkyl)amino; R2 is hydrogen or C1-6alkyl; R3 is C1-6alkyl, aryl, C3-7cycloalkyl, C3-7cycloalkylC1-4alkyl, or arylC1-4alkyl; R4 is hydrogen, C1-4alkyloxycarbonyl, carboxyl, optionally mono- or disubstituted aminocarbonyl, mono- or di(C1-4alkyl)aminocarbonyl, C3-7cycloalkyl, C2-6alkenyl, C2-6alkynyl or C1-6alkyl optionally substituted with one or more substituents each independently selected from aryl, Het1, Het2, C3-7cycloalkyl, C1-4alkyloxy-carbonyl, carboxyl, aminocarbonyl, mono- or di(C1-4alkyl)aminocarbonyl, aminosulfonyl, C1-4alkylS(═O)t, hydroxy, cyano, halogen or amino optionally mono- or di-substituted where the substituents are each independently selected from C1-4alkyl, aryl, arylC1-4alkyl, C3-7cycloalkyl, C3-7cycloalkylC1-4alkyl, Het1, Het2, Het1C1-4alkyl and Het2C1-4alkyl; Q2 is a radical of formula for the manufacture of a medicament useful for inhibiting HCV activity in a mammal infected with HCV. The present invention also relates to the use of said sulfonamides in pharmaceutical compositions aimed to treat or combat combined HCV and HIV infections. In addition, the present invention relates to processes for preparation of such pharmaceutical compositions. The present invention also concerns combinations of the present sulfonamides with other anti-HCV agents and/or anti-HIV agents.