So, can I use Silverlight to make a "REAL-WORLD" app?

Why yes.... Check out Nibbles for the power of Silverlight @ https://nibblestutorials.net/

And for the really cool animations that you always wanted to do. Go to the nibbles site and click on "Blend and Silverlight" then click on "Animations" and behold the cool Animation!

Proudly brought to you by Silverlight & Blend! :-)

Cheers!