I thought up this idea last year and it has saved me from 2 viruses so far.  A co-worker and a friend of the wife thought my idea was dumb at first, and then they were hit with the dbs virus in October, and that latest virus in January.  They laugh no more.

Whenever I forward an attatchment, I always put a personal note, something like:

Hey I thought this was pretty funny,
-Justin

or:

This joke is right on the money, especially for Paul
-Justin

this way everyone knows that when they get my forward, it's safe to open.  I sent an email to everyone in my book telling them to do the same.  When I get an email that does not have a personalized message so that I can authenticate that it was not "auto-forwarded" as viruses always do, I send a reply asking did they send this, and if so, they need to say so or it won't get opened.  If they don't authenticate, I just dump it.  

I suppose if everyone did this, viruses wouldn't get too far.  I suppose until the virus makers started putting in a program that "auto-writes" happy messages, but until then, this looks (to me at least) pretty foolproof.

Unfortunatly, there are viruses that do [b]not[/b] come in an attachment.  You just download the email from the server and then open the mail, that's it.  

Unfortunately, the only 100% sure fire way to avoid viruses is to unplug your computer and lock it in a closet.  Otherwise, a little descression and caution is sometimes necessary.  So what ever works.

CHZ

Actually, the real problem is the use of the modern HTML based e-mail readers such as Outlook, Outlook Express, etc. The virus can easily be embedded within the HTML page as VBScript. Open the e-mail, boom. It doesn't have to be an attachment.

However, I'm fairly certain viruses are not an issue with ASCII newsreaders as these readers do not contain macro processors, script interpreters, etc. They will save MIME data in an attachment, but what you see on the screen is simply a dump of the e-mail message. The reader software makes no assumptions as to the context of the message. There is no support for HTML tags, fonts, images, etc. Nothing but plain text.

If you want to avoid e-mail viruses, dump Outlook and look for an old ASCII e-mail reader. Maybe you'll find one on tucows.