Just make sure that all of your Windows logins are non-Administrator accounts, and that your Windows installations on those computers are up-to-date.
Malware for Windows always assumes what is too-often true: that the users in question are password-free Administrators. In other words, sitting ducks.
But otherwise, the popular term "virus" is entirely a misnomer -- chosen, of course, for marketing reasons. There's nothing biological about a computer program. Computer software installations can be modified without your knowledge i-f you foolishly give yourself the power to make such modifications, but if you "simply don't do that," the program is powerless.
Last edited by sundialsvcs; 09-27-2011 at 08:56 AM.