My data is either stored on or backed up to a RAID5 NAS which, in turn, does a mirrored backup in real time to another RAID5 NAS, with critical backup sent nightly to a backup server I maintain just for myself at my office. My wife uses FireFox and, of course, I had anti-malware installed on the computer she was using AND it sits behind my router's firewall. My data was damaged. However, even with all the anti-malware precautions, she still managed to infect my primary desktop, my laptop and one other machine that sits on the LAN (and probably a couple of the thin clients, but I just rebooted them which is a quick fix to the problem). The problem was the anti-virus software (Microsoft Security Essentials) let this particular thing through. Malwarebytes couldn't detect it, nor could RogueKiller. Webroot did and, supposedly, removed it from the system. However, I wasn't comfortable with that, plus there were other oddities happening, which may have just been damage done by the malware, so I repartitioned the SSD and re-installed the OS.

In other words, all of the usual precautions failed -- I suspect she went to some website and got a particularly nasty drive-by infection.

I don't want dual boot on my primary computer for a number of reasons, not the least of which is I don't want to give up the space on the SSD, and I don't want her to have direct access either to the internal hardware or computers and drives that sit on the LAN. She likes my computer becuase it has a nice, big 32" 1920 x 1200 monitor and won't accept a laptop, of which I have several spares. A virtual PC is the best solution, has the smallest footprint, and appears to provide the best security. All I have to do, in case she messes it up, is rename the backup copy of the virtual machine and copy it to the Virtual PC directory.