You can take a look at https://en.bitcoin.it/wiki/Securing_your_wallet and maybe less directly relevant, but still good information is https://en.bitcoin.it/wiki/Weaknesses .

Personally, I keep my btc wallet.dat file in a AES encrypted diskimage (sparsebundle on OS X) in my Dropbox, and then symlink that file to the place where it needs to be on the computer. My wallet is always backed up, and secure enough (you need either physical access to my computer and get the password right, or, access to my dropbox account and, again, the password for the wallet diskimage).

Quite content with my setup, I just mount the diskimage before I open my Wallet application...