For learning C I recommend Pelle's C. It's a great IDE with everything you'll need and the compiler is C99 and C11 compliant.
+1
For C++ I would probably lean toward Microsoft's MSVC Visual Studio Express.
Visual Studio? Yuk...
I would rather recommend Dev C++ (
http://orwelldevcpp.blogspot.com/)
For Learning C# I recommend the C# Visual Studio Express or Sharp Develop both of which target that language.
Well who voluntarily wants to learn C#? <BFEG>
For Learning Java I recommend Eclipse. It is more nimble than Net Beans
The words "Eclipse" and "nimble" in the same sentence, that's an oxymoron... <LOL>
One of the problems with Eclipse is that they try to use it for everything, including everything and the kitchen sink. Not really what I would call "nimble"...
The basic Eclipse IDE, without any compiler/programming language specific add-ons is a mere 200MB, that's 17x of the Pelle's C 64Bit
compiler+IDE download size...
Ralf