If you are using Office 2007 in an environment where everybody else is using Office 2003, you might have already set Excel or Word to always save to 2003 format, but what about when you create new documents using the New menu? The only choices are now to create files in 2007 format, but we can add the old ones back.
In case you aren't sure what I mean, just right-click on the desktop and choose New from the context menu, and you'll see Microsoft Office Word Document in the list, which creates a blank .docx file.
We can add the old item back to the list with a simple registry hack.
Manual Registry Hack
The "New" items are stored under the file type definition, under a ShellNew key. In order to create a blank document, you have to add a key named Nullfile to the right-hand side.
Open up regedit.exe through the start menu search or run box, and then browse down to the following key for the .doc extension:
HKEY_CLASSES_ROOT\.doc\Word.Document.8\ShellNew
Simply create a new string value on the right-hand side and name it Nullfile. You might have to wait a few minutes before it shows up in the New list, or you can always log out and back in.
You can do the same for the .xls file extension for Excel 97-2003 documents by browsing down to this key, and create the same Nullfile value on the right-hand side.
HKEY_CLASSES_ROOT\.xls\Excel.Sheet.8\ShellNew
For Powerpoint 97-2003 you can browse down to the following key, creating the value again like before.
HKEY_CLASSES_ROOT\.ppt\PowerPoint.Show.8\ShellNew
You should see the items on the right-hand side now, but if you don't you may have to wait a few minutes or log out and back in.
Downloadable Registry Hack
You can simply download, extract, and then double-click on one of the included files to add the information into the registry. Each file is named according to the document type. There's also included files to remove them as well.