Do you really need to learn Silver light. If you want to make a good ASP.NET Project ?

Hello, I've created some projects on ASP.NET, way back 2-3 years ago and tried to use Silver light a little bit. But I found that Silverlight's coding is totally different from ASP.NET. And you have to learn to code the same control in a different way (say Coding GridView Control). Now I've some ideas and I want to implement them. But I'm little bit confused should I start with ASP.NET + CSS or learn Silverlight also. Please guide me...