Utter rot. It's just a bog standard virus. Also from snopes.com:

Although the Postcard virus is real, it isn't a "BIG VIRUS COMING" (it's already been around in multiple forms for a long time now), it will not "burn the whole hard disc" of your computer, CNN didn't classify it as the "worst virus" ever, and it doesn't arrive in messages bearing a subject line of 'Invitation.'

"Never argue with idiots. They'll drag you down to their level, then beat you with experience."