Is stability/security really still an issue for Windows?

With Windows 8 out for a few months and all of the new devices in the market, do the potential buyers still have to be concerned about there computer suffering from "Win-rot", BSOD or malware infections?

I still frequently see commercials on TV for finallyfast.com, cleanmypc.com and all this other shit where the actors are complaining about how much they hate their PC because of popups and really slow performance and get frustrated because the general public see's these kinds of commercials and take them to heart. They expect their next PC to require this kind of service.

So the question is, has Microsoft been able to curb the assault on Windows by now? With Windows Defender, IE10 and the stability Windows 7 has endured (and now 8), is the perception ready to be swing back around?