A new report from Security News Daily raised my eyebrows. You can read the entire article here (reprinted on msnbc.com) but the jist is that PDFs are not always safe. Far from it, about 36 percent of malicious activity comes from PDFs. PDFs are the number one source of web-based attacks. Essentially what happens is code is embedded in the PDF, so when you open it you "unleash" the bad guys.
So what's the bottom line? Number 1 you need to be careful to verify any attachments before opening. This means every attachment. Don't open from people you don't know. Don't open if the message sounds strange or very unlike the sender (their account could have a virus that is sending out messages to all their contacts). Number 2 make sure you have an IT partner that you can call when a virus attack hits. Or better yet, have a strategic IT partner who is monitoring and scanning your network to help detect weaknesses in your network before disaster strikes.