The most important thing you can do is be sure you download the latest updates for Windows. Last week, Microsoft finally disabled the auto-run feature via an update that allowed these viruses to spread so easily. Now, if you stick a virus infected thumb drive in your computer, it won't infect the PC unless you execute the virus file manually. You can read a blurb about it here:
http://www.securecomputing.net.au/Ne...n-for-usb.aspx