It's a nasty little worm. It sends the entire contents of your 'My Documents' folder to everyone in your address book - and any e-mail addresses in any web pages stored in your cache!
More details can be found at:
http://vil.mcafee.com/dispVirus.asp?virus_k=99141&
There's also a fix at:
http://www.mcafeeb2b.com/naicommon/aver ... asp#sircam
I've been sent it several times to my main e-mail account. None of the senders I know, and, I like to think, I'm savvy enough not to open any attachment from an unknown sender, or anything with a double suffix like '.doc.pif' - that's the dead giveaway!
Good luck.