Looking here and there, I found that different versions of MSXML can run side-by-side.
So you can safely install the MSXML4.msi package from the Microsoft dowload page
http://www.microsoft.com/downloads/deta ... laylang=en
The issue - at least for me - was that this package would not register automatically.
I solved the issue by going into that "execute" applet in the Start menu, typed "regserv32 msxml4.dll" and got a message it went fine. Then my MindManager X5 worked again.
Hope this helps.
Raphael