I've got four old desktop computers, some with classified information on them. Those I didn't have keys for were all using pretty old/broken encryption, so I got them decrypted pretty quickly on each machine... So I have full administrative access to each system.

Now I'm wondering what the most effective way to preserve the systems is, while freeing up the actual hardware for re-use.

My ideal scenario, I'd be able to effectively make an image of each system that I can run in Virtualbox, so I can access the documents and applications in their original form. That's because a lot of these documents are in the annoying proprietary formats that plagued the 90's, so converting or exporting them into something else usable is not super likely.

So my question is - what's the most efficient method that /g/ would recommend for imaging the systems in a format that I can mount on a more modern machine?