This worm is no joke. And most virus definitions won't catch it until they're update to 12AUG03. I had to remove it from my boss's computer today. It's a pretty easy fix... Here's how you know you have it....
#1. You're using your computer when a message comes up telling you that the Remote Procedure Call has crashed and your computer will shut down in 1 minute. (THIS IS THE BIGGEST GIVEAWAY!)
#2. Slight performance decrease on the internet (Worm replicating)
#3. The file "msblast.exe" is found on your computer.
What do you do? Well first, you need to fix your Remote Procedure Call vulnerability. God bless Microsoft (sarcasm) for including that security loophole. As thousands of infected computers randomly select IP addresses to send the worm to, the Remote Procedure Call vulnerability is exploited to transfer the files to your system. The crashing problem happens because once your computer is found as vulnerable, the IP address is saved and you will constantly receive the worm. All of this cluttler on port 165 (could be 135, don't remember) causes the Remote Procedure Call (Hereto known as RPC) to crash. Windows XP (especially, but other OSs as well) will shut down the computer if the RPC service fails!
Microsoft has provided a patch for this, simply search for "Remote Procedure Call vulnerability" under Google and you should be able to find the latest patch.
Now... go to Symantec's website and download the W32.Blaster.Worm removal tool and run it.
Of course, this is a dumbed down version of the actual processes that the worm goes through, but I think for explaining to laymen it should suffice (it's probably more than you wanted to know anyway!)
Hope I was able to to help!