In "Windows 7 In Depth", discussing Disk Management (page 718), the authors say:
Caution: If you shrink your system's boot volume, you cannot extend it (unless you want to connect your system's hard disk to another system running Windows 7).
Is this true? If so, it seems rather an oversight. Has anyone tried it? The book might be referring to Dynamic Disks, or Basic Disks, or both, I cannot tell.