Accounts are being hacked everyday, it just make good sense to purchase an authenticator. (or get one free for your phone/pda device) My account got hacked earlier in the year (I was fortunate to be alerted within just 5 hrs via email) Within a few days, got all my items/gold returned)

First thing I did after getting my toons back was get an authenticator, then I set up a totally separate email account for use with Blizzard (not used for any other communications)

Been fine ever since