[Fyron]

Jack Simth said:
not from random downloads off the net, but from boxes sold in stores

AZ didn't specify what the software was, so this seems to be a dubious supporting argument. I doubt that a system with a ton of different media players and disc burners had many of them come from a store, simply because that tends to get really expensive to purchase, and there are so many freely available on the net (even if some are limited feature versions). Even dumb people have only so much money to waste.

Actually, to break a *nix box, you pretty much have to use the root password at some point..

So what? Any home user is going to have the root password for their box, and put it in when it asks for it. An illiterate user won't magically be protected by user permissions, cause he will figure out how to grant them when the box wants them to. That sort of security is merely an illusion of market share; if Linux were to magically gain a large market share, there would be tons of malware and other poorly authored software for it, getting installed on people's machines.

Windows defaults to the only account being an administrative account, which causes issues as basically everything ends up running with administrative-level permissions, so any old program on the box can do mean things to the box.

Which is why MS put UAC into Vista... You have to explicitly press the OK button when software does something requiring admin privileges, even as an administrative user. Obviously it isn't perfect, and dumb users will click OK anyways. Such access protections help with drive-by installers and such, but they do nothing to stop users wanting to install the latest Bonzai Buddy. This is not something you can fix in any technical fashion, regardless of OS. It requires user education.