I'm working on one myself, and for 3D graphics I'm using Ogre3D (its pretty damn good). its LGPL so you wont (necicarily) have to release your source code if thats an issue for you... I'm working on my own networking engine because that was like my "target" as a completed product.... as for physics ( not sure about that) - but I'll probably implement something farely basic...
If you are interested in MMO development but are new to C++ing, then you might be interested to join an existing team such as planeshift (look at their "massively multiplayer online game development" talk on the youtube channel: "googletechtalks")... That might give you a bit of an idea as to how they do it.
Its quite a broad topic to cover - and for a sole programmer its an enoumous task ( I'm not the only person on the team

)....
Also (not sure how helpful it will be) - but theres a youtube channel with the developers of a game for the PC and dreamcast from the user "GyroVorbis" so you might be interested to look there ( though theres no networking, and its more "fun" than "code")...
Finally, you might be interested to look at a few more simpler languages such as python if your new to coding. python addons such as PyGame are good - and as blender3D has a full python interpreter built in, you could use the blender game engine and write some networking if thats what your interested in ( running python on both the client and server?)..
anyway - good luck with whatever you decide to do... happy coding!