I would not change this using Kix.
It would be better if you would set up your shares better.
Use one for both, this saves you a lot of hassle.
Since for Windows 7 it would create the following profile:
\\server\share\userprofile.V2
For Windows XP it would create the following profile:
\\server\share\userprofile
This way they do not interfere with eachother.
However to get this to work you need some additional tricks with NTFS and pre-creating the profile folders (and for that is a trick too) with the respective NTFS permissions.

Also keep this share separate from any Folder Redirection shares.
But this is more of a AD/NTFS thing then a KiX thing.