Creating your whole website using Silverlight isn't usually the approach you'll take--unless you happen to be a company specializing in Silverlight development.
At MIX10, I caught up with Emil Stoychev, founder of SilverlightShow. His company, CompletIT, located in Sofia, Bulgaria, created a very slick animated website entirely in Silverlight. It has everything from background animation, to cool folding effects, to
a full portfolio to...flying pigs!
Definitely worth a view.