Here is a list of resource available online on Internet for Duet.
Duet official Website: http://www.Duet.com
Duet Home Page on MICROSOFT.COM: http://www.microsoft.com/Duet
Duet on TechNet: http://technet.microsoft.com/office/bb267348.aspx
See online Duet Demo: Duet online Demo
Some Duet blogs: