You are probably already aware that you can use the MFC socket classes in an ATL object however it is probably more efficient to use the Winsock 2 API. The following technical article in MSDN will give you a simple class that could be incorporated.

Power Outlets in Action: Windows Sockets
Ruediger R. Asche

However, what would you be trying to acheive through ATL? I can see all kinds of problems if you where to try and use things like MTS/COM+, for example state. Could you elaborate a little more on what you are trying to achieve by using ATL.

Neil