Does the file open on your computer still. If so just resend the file. Easier than fighting to find a solution.
Office 2003 has a repair option which is worth a look. Go to the open option if I remember correctly and you can then choose to sort it if it can be. However most likely made easier to resend it. Alternatively try putting the file in a zip or rar file using the likes of click here or click here. The former being recognised and openable on any windows XP machine.