I am developing an online strategy game using .Net v2. Although the game is primarily strategic, it does have some tactical elements that require reasonable network performa
Although this question is rather old, a somewhat higher level system developed specifically for games is APlay - among the supported platforms is also C#. There are evaluation versions and it is free for personal use.
You define your game objects in an UML alike fashion and an online code generator creates assemblies containing your game objects. Sending state updates is then as simple as calling setter methods.
Not the right thing, if you want to cope with sockets by yourself. Please also note that I am a developer of APlay so this is a biased answer.