On virtualfestivals.com! Apparently Muse received more votes than any other winner in the other categories!
... Perhaps a more worthy winner is Muse, who pick up the prize of Best Live Act. 2004 has been the year to cement Muse as one of the best live band's in the world and their epic, space-spanning sound deserves and demands no less than the biggest stages. They reached stratospheric levels during their headline performances at V Festival and Glastonbury, as well as making the rest of the world stand up and take notice with several huge festival shows overseas. Not only have Muse grown musically, they have suffered tragedy and battled through adversity. Following the death of drummer Dom's father, the band refused to cancel their forthcoming gigs and vowed to carry on in his memory. Perhaps this brave show of dedication to their fans helped win them the award. Whatever your reasons, Muse got more votes than the winner of any other category.
2nd - Franz Ferdinand
3rd - Basement Jaxx