There's lots of bleary eyed network admins out here this morning. Looks like another* MS SQL server vunerability being exploited out there. We know of at least one server that was driving 80Mb/s to the Internet.
All this can be avoided by patching your operating systems correctly. Most users can go to their Internet Explorer browser (the big blue "e" on your start menu) and on the Tools menu, choose Windows Update. Follow the instructions. For whatever other beefs one might have with Microsoft, they do their critical update service very well. Its free, and it could save you thousands of dollars.
If you run if you run Linux or some other operating system please consult your manuafaturer's update pages, or install some program to automatically download the required software.
* Symantec reports that this activity is related to vunerabilities discovered in 2002, and at the time this is posted the incident has not yet been published at NIPC, CERT or similar sites.