I have a big project in my head, it should be cross-platform (Win, Max and Linux), online (Client - Server) and with 3D graphics. I would like some suggestions to start with the right things.

Currently I'm a PHP/MySQL coder, I used to code in C and Pascal on DOS ages (Borland Times ;)), my C knowlegde need a refresh but it's ok.

I guess C++ it's the right language. What platform and what i should use to code? I can choose from all three platforms. My idea was to use Visual Studio 2010 C++, but i'm not sure if it support Native code.

What kind of libraries should i use? I guessed OpenSSL for the login, OpenGL for graphics part. For the Audio or the GUI? Any other suggestions are well accepted.

I know it's a "BIG DEAL" but I have no rush and it'll be a free-time project, only for my pleasure.

Thank you in advance.