That's what Microsoft invented Bitlocker for: http://windows.microsoft.com/en-us/windows7/products/features/bitlocker. But many external hard disks (not all!) come with their own encryption software.
Since you're a company it could be an essential requirement is that such an encrypted disk works on multiple PC's (all PC's used by all your DJ's) and nowhere else. Thaat would be a nice selection criterion.
It's your choice what encryption to use. And very important: it's your responsibility to keep an unencrypted copy of everything you put onto it, just in case something happens. In fact, an unencrypted copy and - of course - a backup of that unencrypted copy.
Kees
I run a mobile DJ company and we use external hard drives. The problem is, I want my hard drives to be unlocked automatically on boot up *IF* it's plugged into the correct computer. If someone were to try and copy the files away from the drive or plug it into another computer, I don't want the drives to work. Any idea of a software that will do this?

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