C# Social Networking: what to use

Question

My goal is to create a social network website similiar to facebook, twitter etc......
Question 1: Do you recommend using third party controls why and why not, 

Question 2: I want to either use asp.net or silverlight or i can use both together, which do you recommend using?

Question 3. If you were creating a social networking site using infragistics controls, would you silverlight, asp, or light switch infragistics controls? or  telerik controls etc....