1) IIRC, The Windows NT family had more granular level permissions than Linux. Granted before XP Windows was quite insecure, as I said in my original comment

2) Still we do see a lot of bugs and exploits that affect large swathes of Linux machines.

3) My entire point is that popular OSes that are used by nontechnical users that allow third party installs

4) Even OS X got a lot of burn for sanboxing apps and making third party apps difficult to install. They tried difficult UAC with Vista and it didn't go so well.

There isn't much stopping Linux malware in repos if the Linux desktop gets more popular. http://www.zdnet.com/blog/hardware/how-much-more-malware-is-...

Heck, even kernel.org was rooted and they still haven't revealed what happened. Not to mention other distros which were also compromised at some point.

5) http://www.pcworld.com/article/2099421/report-malwareinfecte...

6) Which ones? (apart from RT ARM machines that were a total flop in the marketplace and are like iPads)