Yes - I did make a backup - and one that is encrypted too. And damned if I know what to do with it.
First, close the Bitcoin-Qt client.
Then rename (rather than delete) your current wallet.dat just in case .. or move it elsewhere, but don't overwrite your backups.
Then copy the BTCBackupEncrypted.dat and save it as wallet.dat in your Bitcoin data directory.
Launch Bitcoin-Qt.
Your funds should be there (presuming you've made less than 100 transactions since March 24th).
(I'm not sure with v0.8.1, you may need to run Bitcoin-Qt with -rescan if the balances are not accurate.)