The bottom line is that if you have one of the estimated 300,000 infected computers, come Monday morning you will not be able to access the Internet. If you are not up to speed on this threat, I suggest you read the FAQ in the link below. Even if you think you are clean, it is worth going to the site which checks your computer. There are different ones for different countries and they are listed within the FAQ (follow the links in the section "How can I tell if I'm infected?") .