I was trying to create silverlight project in my laptop and I got error that you need to install Silverlight Developer environment, this was strange to me because I had silverlight developers runtime environment installed on my machine. I clicked on the link provided by visual studio 2010 and downloaded it again and when I tried to install it I got this error

So I decided to search in google and found this thread. which helped to get link for 64 bit silverlight developer environment.

After installing Silverlight_Developer_x64, I am able to create silverlight project.

Hope it will help someone.