You can go to the Microsoft Windows Update site and read about it. They expect a fix next week, they're testing it now. Basically, they've figured out a way to embed a virus into pictures, etc. that you open on a website or in an e-mail. If you are on a network, it could then allow them to create a user account with all of the same priviledges as you have, then they could do pretty much anything they want. Really nasty. Suggest you only go to sites you know and trust, and don't open anything unless you know the person who sent it, and you trust them.