Michael, my goal is to extract all documents embedded within any given
compound document.  Here is the current revision of my code:

//6) Get a pointer to the IPersistStorage Interface.
//comObj = Word, Excel, etc.
Guid IID_IPersistStorage = typeof(IPersistStorage).GUID;
IntPtr pIUnk = Marshal.GetIUnknownForObject(comObj);
IntPtr ptrStorage;
Int32 r = Marshal.QueryInterface(pIUnk, ref IID_IPersistStorage, out
ptrStorage);

//7) Load the COM object from the storage.
IPersistStorage per =
(IPersistStorage)Marshal.GetObjectForIUnknown(ptrStorage);
r = per.Load(Marshal.GetIUnknownForObject(store));

//8) Create new storage and save to disk.
IStorage temp;
StgCreateDocfile(@"D:\Data\Result\Output" + count,    
STGM.READWRITE|STGM.SHARE_EXCLUSIVE|STGM.CREATE, 0, out temp);
OleSave(per, temp, false);

I understand that this approach will not work for all documents.  For
non-office documents I have a different approach where I where I write the
"CONTENTS" stream to the file system.  This works for PDFs for example.

The above approach works perfectly for all office document types except
Excel.  Excel documents are created, however they seem to be lacking some
information and will not open natively.  I can "fix" them by dragging them
into IE, where they can be viewed, and then saving them.  This work around is
not acceptable to me.  

Excel storages are associated with the clsid of Excel.Application.  However,
I can't get an IPersistStorage interface for this object, instead I need to
use the clsid of Excel.Sheet to get any joy here at all.  Wondering if my
problem is somehow related.

Regards,
Heath.