Everybody is afraid of computer viruses now a days, so whenever we come to know about a new virus, we want to let everybody know about it. A hoax really thrives on this urge, so whenever you receive a mail which talks about a virus and tells you to forward to your contacts so that they can be aware about it too. Stop and first try to find if mail talks about a real virus or its just a hoax.
These hoaxes have become so frequent these days that major anti-virus companies now maintain a database of hoaxes beside viruses. I recently received an email talking about an Olympic Torch Virus. I did a quick search and found that its a hoax.
So in the future please do not pass on such messages. Passing on messages about the hoax only serves to further propagate it.