If you are wanting to market your game, definatly DO NOT TARGET IT AT A CERTAIN OS, especially one as archaic as DOS.
You can probably go right down to you local book store and get Game Development books and Game Programming in C++ or some other language.....they go from beginning to end, with examples. You will also make yourself marketable as a programmer in general.
As for language, man, there are a lot of opinions. I'll go ahead and lay down some facts, (at least ones that I know)
Free (IDE's, Compilers, API's, SDK's)
Jave (Netbeans, The rest comes with the SDK from Sun, available at
www.sun.com
C/C++ (Dev-C++, Quincy 2005, the rest is available by google)
Costly
Any thing by Microsoft I.e. Visual Basic, Visual C++, C#, J#, Visual Studio
I will admit though, Visual Basic is probably the easiest language I have ever worked with. C/C++ will run more effeciently, while Java is gaurenteed with a minimal amount of extra work on your part to run on about any system. I will say that almost any "beginner" book you get will supply you with at least a trial version of the software needed, if not a permanant copy.
Good luck