Can I keep my pages and custom ArtSets stored in the TwistedBrush installation folder when running Windows Vista or Windows 7?
Yes, you can choose to run TwistedBrush as an administrator in which case the pages in your books and custom ArtSets will be stored under the installation location for TwistedBrush. Just like they do on Windows XP.
Right click the TwistedBrush shortcut on your desktop and choose Properties and set compatibility to Run as Administrator
When running a program with administrator rights in Windows Vista or Windows 7 the default is to prompt for your approval each time that program starts. It is possible to disable that as well by during off User Account Control for the user account in question. But this isn't required and turns off one of the security features of Windows.