Our old virus friend Sobig is back - this time in a more virulent strain called W32.Sobig.F@MM. All indications suggest that this is the worst strain yet - so far today I've received ten e-mails infected by it. If you've been infected, Symantec have created a fix tool for you to clean your system with.
There's also a new "friendly" worm out there on the web called W32.Welchia.Worm that downloads the patch to fix the vulnerability last weeks Blaster worm exploits. Despite its good intentions it still causes problems, so if you've been infected, Symantec have created a fix tool for that as well.