Search, and you shall find. One of the many problems of dealing with VHDs is that they can take ages to create. More specificly, the fixed VHDs can be very slow. This is due to clearing the entire VHD with zeroes. Creating any file that is gigabytes long is bound to be painful.
The Virtual PC Guy (Ben Armstrong from Microsoft) has come up with a solution. It entails not zeroing out the file and creating the VHD footer at the end. Very fast and just what most people want. The only concern is security related to the VHD claiming deleted data since it was not cleared. For most people this would not be a major concern under certain conditions (like a new disk). However, this sounds like more a file system problem. When files are deleted, they should be cleared then. There might even be a NTFS option to do this. Let me know, please?
Virtual PC Guy has also been nice enough to provide the binary and source for his tool. This is a very kind gesture and I say thanks.