How do I get formatted JSON in .NET using C#?

I am using .NET JSON parser and would like to serialize my config file so it is readable. So instead of:

{"blah":"v", "blah2":"v2"}

I would like something nicer like:

{
    "blah":"v", 
    "blah2":"v2"
}

My code is something like this:

using System.Web.Script.Serialization; 

var ser = new JavaScriptSerializer();
configSz = ser.Serialize(config);
using (var f = (TextWriter)File.CreateText(configFn))
{
    f.WriteLine(configSz);
    f.Close();
}