Ideally mIRC should store data in the same way on all versions of Windows. If I made it store data using one method on Vista and another method on all other versions of Windows, that would likely lead to other issues, ie. what if an XP user tries to share a script/installation with a Vista user, or vice-versa? It would be better to make sure that mIRC behaves the same way on all Windows versions. So yes, the change would affect all users even those who do not use Vista.