I'm suprized no one suggested .NET. The .NET framework is a beautiful thing. I want C# to have the rest of my kids
Seriously tho, I started as a vb codemonkey and now I spend most of my time doing C# projects. I know some C++, VB inside and out, php, mssql, mysql (they need sp's damnit), perl, and enough java to be dangerous. But for windows applications, C++ or anything in the .NET framework would work good.