When i used visual studio 5.0 it should compile c code as long as the header files and lib. are there for the compiler to find. In fact most C++ compilers like G++ will compile C code just fine. But i'm not sure how well.. If you are targeting a platform then you can change the header files and lib. within you IDE and Compiler.
Visual Studio has a great debugger that no other Compiler that i have seen can compete with. I have been using gcc darwin10 4.2.1 and find the debugger is basically just the one you can getfree with any linux flavor. I recommend you learn both on a plain vanilla gcc compiler and also try visual studio which costs money. The express edition does not allow the use of threading and several other things that I forgot about. Visual Studio 5.0 should be ok to use and the debugger is much more human friendly then the one commandline version called GDB. Try DDD on linux which is similar to XCODE's debugger.
Although C++ and C are different you can compile both together. But you should understand each ones flaws and good points. C code is faster, but C++ is much easier to write and manage larger code. C++ is object oriented but C is procedural while they are both imperative languages. I would suggest learning objective-C since you can use both C++ and C libraries. Using the features you like in all three languages!!!
