SharePoint Server 2007

"In Word 2003, you can compare documents side by side. Open two documents. Then, from the Window menu of one of them, select the Compare Side By Side command. If you have only two documents open, the command will automatically choose to compare them. If you have three or more documents open, you'll have to select which document to compare with the current file.

A floating toolbar with two buttons will open. If the button on the left is selected, Word will scroll both documents at the same time. Press the button on the right side of the toolbar to return to where the cursor was located when you started comparing."

SPS webpage can detect you have installed the Office 2003 and run local dll to implement some SPS function, e.g. multi-file upload only works when you have office 2003 installed.

Integration with Office XP is gone.

You will get guys telling you that you can integrate with SPSv2 if you install a backwards compatible document library - but that’s really just putting a bit of SPS 2001 on the server.

Believe me, check-in, check-out, which are themselves very basic, are not available from inside Office XP, or even from the context menu in Windows Explorer.

The ONLY option you have is to use the web interface to check-in or check-out.