Well I think more people will start using macintosh anyway, because now they have started using intel you can switch between Mac OS X and Windows easily.
A lot of computer magazines say that most notebook computers will not run windows vista, and that ones that are windows-vista compatible will only just run it.
Look out for this logo on new PC's
At my local datacenter, on the computers they use sophos antivirus, it updates itself everyday at a time that you can set, and it doesn't interrupt anything else.