If you follow the advice, given by others above, and still have a problem to solve I recommend the following.

1. Re-inform your company of your need to take projects home (I assume the reason for the laptop)

2. Also inform them that their anti-audio file policy disqualifies your personally owned laptop from being used as the vehicle to take your projects home.

3. That if your productivity is to be maintained at the present level, they need to supply you with whatever sized firewire harddrive your projects require.

Then store all you work related files on the firewire hard drive and take it back and forth to work instead of your personal laptop.

If the soloution to the problem costs the employer money, you may see them back off.

my two cents.

It would work as long as it isn't opened. The password only keeps it from being mounted. The way I understand it, if the disk image is opened, then it mounts as just another disk with its files completely visible to the rest of the computer.

how bout making the folder with the files invisible? There is a neat little program that will do this for you. It is called hide folders and is free. Its from altomac www.altomac.com.

Encrypt it before hiding it. Hiding it does 100% of nothing, unless the person is a COMPLETE moron. And even if they are, they could still stumble on it. So, steps to securing your computer

1) Just turn off all the sharing stuff. Turn on the firewall if you are paranoid. Turn on stealth mode if you are absolutely paranoid. Now there is no way they can get on your laptop via the network, at all.

2) Use a password protected screen saver (if you are using it) with an activation corner for quick lockdowns. Disable automatic login. And if you are paranoid, use file vault. Now, there is no way they are going to get at your comp unless you unlock it for them.

And, umm, thats it. The mac is more or less secure by default, so huge changes aren't needed. Actually, assuming default settings, no changed are needed at all.

And diplomacy is always the better route, use those steps ONLY if you have to.