Mal,
I know that when you install Office 2007 along side with office 2003 there
is an issue when all office documents open up with Office 2007 applications.
Designating the extension and assigning it to the correct App (Word, Excel or
PowerPoint) didn't help me. Explorer > Tools > Folder Options....
I know that you are asking about Office XP and 2007, chances are you will
run into similar issues.
Also, Outlook 2003 and 2007 can't be installed on the same machine according
to Microsoft (not sure about Outlook XP and 2007). According to other forums
there are also issues when Access 2003 and 2007 installed on the same system.
I'm assuming the same goes for Office XP.
Installing both versions of Office is usually not a problem, but designating
2003 or XP in your case is probably what you will have a problem with.
If Office XP is already installed, pop-in the Office 2007 CD and then go to
Customize (I'm pretty sure it`s customize) there will be an option to leave
Office XP installed and not remove it when installing 2007
I hope this helps.