If you normally use Outlook Express to read your mail, you may want to find an alternative.
The worm uses a program bug in Explorer to execute (run) itself, you don't even have to open the attachment. In fact, you don't even have to read the e-mail. Once it loads, it runs all by itself.
But, fortunately, it can only do this from Outlook Express and ICQ.
In reality, there are two worms roaming about right now. One of them will send your keystroke information to the person who wrote the worm... so that person can get your usernames and passwords if you happen to type them in.
If you want the links to more information, guppygrrl has them posted here: http://www.livejournal.com/talkread.bml?itemid=16693001&nc=4