I'm one of the lucky few who got hacked.
It's a wakeup call so now I do just about all Pre suggested.
I have ordered an authenticator and it will probably be here before I get my gear back ( 8 days and counting for the gear ).
I also went to an online password generator site and had it generate a totally random pw for me THEN swapped it around and changed it because I am now paranoid, c & p into a notepad txt file which I gave a random name and I ctrl c . ctrl v my new pw into wow.
I also have updated versions of Malwarebytes, avg ( both free ) and Kaspersky running all the time. I have also changed my WoW registered email address and use a random pw on that as well.
On another note, there have been some random ingame mails arriving offering Cataclysm Tests

I also got one of THEM !!
They are obviously fakes and designed to get your account details so you can finish up like me.