I want to start to work on one application. I wonder if it is better to work in Visual Studio Express version in C#, or to use Netbeans and Java, an open soruce IDE?
I plan to this program may one day be commercial and that can be downloaded from the Internet.
Please include more information. Posts like this usually result in a flame war. Firstly, if your application is supposed to target only Windows and nothing else, then C# may be an option, otherwise, it has to be completely command line or run without errors on Mono and Visual Studio (easier said than done, considering there is no WPF in Mono as of yet.)
If this your first language, I would recommend neither. They are both quite difficult to begin with and you will get stuck in the syntax, instead I would recommend Python. It will get you up to speed quickly, and then you can move on to maybe Java or C#.
Java and C# are very similar. Here are some differences:
In the end, you decide.