@MasterRanger: Yea.  The whole CanExecute thing.  Take a look at this video.

http://www.lab49.com/wp-content/uploads/2011/12/Jason_Dolinger_MVVM.wmv

It helped me understand, hopefully it will help you.

Reference: Here is the page where the link to Jason's wmv lives.  http://blog.lab49.com/archives/2650