Here's a new approach to linux adoption. Create a linux distro which converts a Windows machine to linux, marketed as a way to solve many of your virus/malware/phishing woes.

Yes, for a long time linux distros have installed themselves on top of a windows machine dual-boot. And there are distros that can run in a VM on windows, or look windows like, but here's a set of steps to go much further, thanks to how cheap disk space is today.

• Yes, the distro keeps the Windows install around dual boot, but it also builds a virtual machine so it can be run under linux. Of course hardware drivers differ when running under a VM, so this is non-trivial, and Windows XP and later will claim they are stolen if they wake up in different hardware. You may have to call Microsoft, which they may eventually try to stop.
• Look through the Windows copy and see what apps are installed. For apps that migrate well to linux, either because they have equivalents or run at silver or gold level under Wine, move them into linux. Extract their settings and files and move those into the linux environment. Of course this is easiest to do when you have something like Firefox as the browser, but IE settings and bookmarks can also be imported.
• Examine the windows registry for other OS settings, desktop behaviours etc. Import them into a windows-like linux desktop. Ideally when it boots up, the user will see it looking and feeling a lot like their windows environment.
• Using remote window protocols, it's possible to run windows programs in a virtual machine with their window on the X desktop. Try this for some apps, though understand some things like inter-program communication may not do as well.
• Next, offer programs directly in the virtual machine as another desktop. Put the windows programs on the windows-like "start" menu, but have them fire up the program in the virtual machine, or possibly even fire up the VM as needed. Again, memory is getting very cheap.
• Strongly encourage the Windows VM be operated in a checkpointing manner, where it is regularly reverted to a base state, if this is possible.
• The linux box, sitting outside the windows VM, can examine its TCP traffic to check for possible infections or strange traffic to unusual sites. A database like the siteadvisor one can help spot these unusual things, and encourage restoring the windows box back to a safe checkpoint.

The goal, however, is to not have them run the VM very much, like Mac users run Parallels. Instead, you want to present the user with a system which is, at first glance, only subtly different from the Windows interface they have trained on. The desktop works the same. There is a Start button with similar menus. Where it has to be different, there is help about how it is different, such as the new "control panel" and of course installing hardware and software. So they don't feel scared when they first try it. And of course there needs to be a backup of any changes made to the bootable windows so they can be told they can go back if they need to.

I could see parents installing such a system because many parents lament about how their kids are always downloading stuff and infecting their machines. A way to stop these infections, or back them out -- or have a different sandbox for each user which doesn't bother the others -- would be popular. A way to get away from the problems of windows without the fear that they will no longer be able to run an important app.

Yes, there are going to be hardware issues. People who have hardware that isn't as supported under linux will not be able to go this route. But that's fewer and fewer people, especially now that more hardware is USB based and the virtual machines can even hand USB peripherals over to the guest OS.

Now what would pay for building this distro, and the hard work of tools that can import all those windows settings into the linux programs? That's the hard question. The package could consist of a free linux and some commercial add-ons that do the windows importing, so it could be sold. But since it might trigger a lot of switching to linux, the usual motives might apply. Being able to tell the user "Install linux, you won't see much difference and you can go back" could win a lot more converts.