"NOT_ENOUGH_SPACE": That's what it is!

Here's the problem: Your Windows 8 Developer Preview won't start and you will most likely get error messages not always easy to understand. However, there is one single error message which is self explanatory: VHD_BOOT_HOST_VOLUME_NOT_ENOUGH_SPACE. Your Windows 8, at run time, will occupy all the space assigned during setup. For instance, if you assigned 50 GB, it will gobble up that amount, it doesn't matter that your file explorer shows that the Virtual Machine Hard Drive Image (a huge file with a .vhd extension) holding the virtual machine, is just 17 GB, as in my computer. Obviously the solution is to give more room to the partition where Windows 8 is located. Ideally you will use a dedicated partition for a different operating system.