Had the same problem but think I’ve worked out a fix not that we should have to do Microsoft’s work for them but here goes.
The update seems to need a file called PA561401.cab before it can configure itself so what I did was found this file by inserting the Office 2003 CD Rom, doing a search of its contents by right-clicking on the CD Rom drive within My Computer and once you find the file relevant to Office, copy this to the following location:
NB If you can’t find the MSOCache folder on C, you need to tweak you folder view so that it displays folders that are normally hidden (this can be done within My Computer via TOOLS > FOLDER OPTIONS > VIEW and then make sure Show hidden files and folders is ticked.
Now, with your CD Rom still inserted, revisit the Microsoft Update website and try to install KB2493523 again,
You can also download the update file separately if that helps from
Hope this works out for you.