BOAC, Virut is a particularly and buggy polymorphic file infector.
Almost all the advice I've read on the forums that deal with this sort of thing is basically that a format and re-install is usually the only option.
Many different - and not necessarily executable - files can be infected by this one.
I think that probably the only way it could be fixed is by using a bootable disk (Like Linux Puppy or similar)to delete all infected files from outside Windows, and then carry out a repair install, but if there was even one file left that was infected, as soon as Explorer processed that file, it's all on again.
Good luck.