VC++ 9 is OK. You just have to ignore/disable what you don't need, and realize that it really wants you to write C# or "Managed C++", rather than pure C++ so watch out for that.

But I'd also check out Qt Creator: http://www.qtsoftware.com/products/appdev/developer-tools/developer-tools (download at the bottom of http://www.qtsoftware.com/downloads). It's intended to be used to use Qt to make GUI applications but you don't have to use Qt. It's a nice simple interface, no feature bloat (yet?).

Open source system for interoperable 3D environments: http://www.interreality.org/
(Also useful for other stuff than 3D!)

And we've put a lot of work into trynig to design a flexible structured system, and also actually making the networking perform efficiently for this application (no conneccting to random SQL databases or using HTTP over TCP sockets and stuff like that!)

Check it out. We're currently revising a some of the core library, but we will soon need people to help make the end user application have more features and work nicely, and also need people to try making 3D worlds and other content.