According to Snopes, this is a hoax which has been around for about 10 years. While there's no question that computer viruses (viri?) are dangerous, even the free anti-virus programs will stop 99% of them when used properly and updated regularly. Careful and cautious browsing habits will prevent 99% of the rest. Forwarding strident warnings such as this one without first researching them only adds to the confusion and fear. A simple check on the McAfee or Norton websites will tell you whether the warnings are real or not, and Snopes, while perhaps not perfect, is still a good resource for things like this.