Should the normal anti-virus programmes prevent this or is there some specialist software he could get?
As I understand it, regularly updated anti-virus software should find and remove most of these - the older the malware, the more likely it is to be found and removed successfully.
Where anti-virus software falls down sometimes is with the latest threats - which are sometimes missed, sometimes detected but unremovable (in the latter case, there is often a threat-specific removal tool) - and with the curious distinction between viruses and spyware: there are some things that you certainly don't want on your comptuer that don't seem to be targeted by anti-virus software. This is decreasing a bit, but it's why we usually advise both anti-virus and anti-spyware software (e.g. AdAware, SpyBot Search & Destroy or Microsoft's Anti-spyware beta).