MS VPC shrink disk

If you are wondering that you can't find the task to shrink the virtual disk of your virtual machine, it's a kind of hidden.
First you have to mount this image in your VM and run the tool: C:\Program Files\Microsoft Virtual PC\Virtual Machine Additions\Virtual Disk Precompactor.iso
Then you have to shut down the VM, start the "virtual disk wizard" of VPC, select "existing disk" then "Edit an existing virtual disk" choose your vhd and finish it with “Compact it”.

Detailed description is available here: http://technolochief.wordpress.com/2008/11/28/shrink-vhd-files-in-microsoft-virtual-pc-2007/