Depends what the executable is going to do... My very strong advice is to learn C. Everyone thinks that C is deprecated and useless, but it is the foundation of all programming languages and is the most powerful Unix language of choice. Many big name companies are hiring with specific requirements of a knowledge of programming C.

However, if you want to start developing Windows GUI I would go with Visual Basic. It isn't all that powerful (although the .NET framework helped this a great deal), and is considered by many to be a "wussy way out" but it can get the job done quickly.

Regards,
Patrick