@the_clown:
The thing is: Visual Studio is not only for C++, but for Software Development. In the bigger versions (Ultimate e.g.) you have a huge pile of refactorings, code analysis, debugging tools, sql server integration, web server integration. You have UI designers, UML->Code-Convertes, Collaboration toolsl, ...
GCC is just a compiler suite, Code::Blocks a lightweight IDE. Visual Studio is a heavyweight IDE. You don't really need any other tools except Visual Studio to realize a project in any size.

Also a personal preference: IntelliSense is just the best code completion...