A while ago I talked about why it takes so long to create a virtual hard disk, and a lot of people came back and said that in controlled environments they were willing to take the security risks / implications involved in order to have quick creation of fixed size virtual hard disks.
In response to this we have made a tool available that does just this:
This tool allows you to create fixed size virtual hard disks very rapidly. You should be aware that the technique used means that it is possible to access data that was previously deleted off of the physical hard disk by running data recovery tools inside the virtual machine. As such you should only use this tool when you can trust all users of the virtual machine.