I'm trying to compile my project with Asio support for Windows CE platform. 
I think, I don't need to define  _WIN32_WINNT or _WIN32_WINDOWS but 
when compiling Asio headerI get this warning: 
"Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example:..."
I find this warning coded in "socket_types.hpp" file.
I'm using Boost library 1.40.0.

How can remove this warning message?
Can I ignore it?

Thanks.
Carmelo