This lead me to another thought though, back to Ubuntu on the desktop. Suppose a user does get a virus that deletes files. Well, the system is safe since the virus doesn't have root access, but does that matter? The system is easy to format and reinstall. Takes a half hour. However the files that are in the user's home folder (which are accessible to the virus) are much more valuable to the user. All the documents, photos, etc.
Linux geeks argue too much that "oh, if a virus gets on your system it can only affect the files that it has access to." Well that's still a problem! Those files are the ones that are irreplaceable, not the files outside of /home. A simple script going
rm -rf ~/*would be enough to really fuck up someone's system.
Lots of people are computer illiterate (anybody who has worked in tech support knows this). It doesn't matter what OS they're using, if it gives them the ability to run programs and it gives them to ability to modify their files, then there is the possibility of files getting wiped out. Unfortunately to get around this security risk we have to give up a lot of convenience. How annoying would it be to either have to type in a password every time you want to modify your personal files?
So there is no way to be perfectly safe, unless you snip that network cable (wireless users are screwed - just kidding). Don't use Linux assuming that you are invincible.