where can I find the silverlight 4.0 for the production server ?
For this need to install vs 2010 ?
or only need to install 4.0 from where can I find the 4.0 for the production server ?
is there any license for the same or its free ?
There isn't really any concept of setting up a "Production" server for Silverlight itself. You would normally just configure the object tag in the html like this:-
<object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%">
<param name="source" value="ClientBin/YourApp.xap"/>
<param name="onError" value="onSilverlightError" />
<param name="background" value="white" />
<param name="minRuntimeVersion" value="4.0.50303.0" />
<param name="autoUpgrade" value="true" />
<a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50303.0" style="text-decoration:none">
<img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/>
</a>
</object>
This will allow any clients that don't yet have the RTM Silverlight 4 plugin to download and install from Microsoft.
If you are talking about the server-side components needed to support a silverlight app that you may have built with VS2010 well thats a very very good question.
If you were to create a Silverlight 4 Business application from the standard template in VS2010 you will end up with a web app targeting .NET 4. So that application will require that the server to support ASP.NET with .NET 4 on the server.
I'm sure its quite possible to develop a Silverlight 4 application that uses 3.5 on the server-side. However its likely that developer experience in VS2010 is going to be hard core since I suspect many of the conveniences created to make developing such apps speedy will not work. Of course this only a suspicion, I'll try to give it a go sometime to see what the realy experience is.