As mentioned by others, simply splitting the wallet, or even an encrypted volume or archive containing the wallet, is not secure. An attacker does not need a whole wallet file to steal from you. All they is a whole private key to an individual address (or enough of it that they can brute force the missing piece) to steal any coins received by that address. With the OP's method, chances are an attacker could steal most if not all of your coins with only one flash drive and your password.
Well, I solved this.
I made a SIMPLE solution, which hosts the entire Bitcoin data (~/.bitcoin) directory, within the "Ubuntu One" free cloud service... Ahh! 100% encrypted by the way...
With no third party softwares.
Take a look at this:
Wallet in the Cloud - Keeping your Bitcoins encrypted and saved into the Cloud! http://forum.bitcoin.org/index.php?topic=22386.0
What do you guys think about my solution?!
It is really easy to do by everybody... No complications.
And it can be easily changed, or used with a USB pendrive instead a Cloud environment... But always use a Live CD, even to mount your encrypted USB Pendrive.