What I'm taking about here is a way to have many VirtualBox machines based upon a single hard drive image. There are many reasons why you might like to do this, but the most compelling is probably saving time by not having to install an OS over and over again, especially useful if you do anything like software testing. Our goal is a single vdi (virtual disk) file which contains a vanilla installation of our favourite OS which we can then use to conjure up a fresh new machine in a jiffy. Assuming you already have VirtualBox installed our first step is (maybe for the last time ever!) to install our OS into a new virtual machine. Now I shan't go through this as it's pretty straight forward and if you're reading this it's the sort of thing you have probably done a hundred times before. One thing of note during the initial setup is the 'Virtual Hard Disk' configuration. Be sure to allocate enough space to allow for all potential applications of the image. It wou...