If you try to install Office 2003, it is going to ask you for the product key and will probably give you a hard time about using that license since the key is already registered.
Maybe you could try using the Microsoft forum first to see if there is a work around.
Here is a workaround I found in Google:
http://answers.microsoft.com/en-us/o...0-594f65f9f45b
Maybe that will help. Basically you download a trial version of MS Office 2007 and use an Outlook connector to copy your PST file over to Windows live.
If you still have trouble, please PM me.
Z