guys, please never do any of these things on a pc that you're using to access bitcoin:
-use Windows as operating system (use Linux instead, 'Mint' is a good variant)
-use Flash in your web browser
-use Java in your web browser (not to be confused with javascript, which is mostly ok)
and always do this:
-use two-factor-authentication
-make backups on at least one external medium that is disconnected from power and from your pc while not in use for the backup process
The worst part is really using Windows without 2FA (two-factor-auth). That's just asking to get your stuff stolen.
Good suggestions, I think 2FA is the most important thing. Mac, Windows or even Linux, without 2FA you are just asking for trouble. We even limit automatic withdrawals to those using 2FA, because hacking and phishing attempts are just inevitable