Vista inspirat stores all your current files in another folder in the WINDOWS directory and when you uninstall the BricoPack, it simply restores all your files (like your icons, etc.).
If you don't want your Shell32.dll to be modified, then don't install Vista Inspirat, but there's nothing wrong with modifying that file, so don't be afraid of installing Vista Inspirat.
But be careful! Don't install Service Pack 3 while you have installed a Bricopack! 