With the default installation you can find these files in C:\Program Files (x86)\Telerik\RadControls for ASP.NET AJAX Q3 2010\Skins.
All the best,
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!