The first thing you need to know about Win Forms is that they are not an upgrade, enhancement, new version, or anything else of the Microsoft Foundation Classes (MFC). They are a brand-new, truly object-oriented Windows GUI implementation. A few classes have the same names and support the same functionalities, but that is where the similarities end.
Win Forms have a much stronger resemblance to Visual Basic's (pre-.NET) forms. In fact, Microsoft has taken the Visual Basic GUI development model of forms, controls, and properties and created a language-neutral equivalent for the .NET Framework.
When you create Windows applications with the .NET Framework, you will be working with Win Forms. It is possible to still use MFC within Visual Studio .NET, but then you are not developing .NET Framework code. However, once you have worked with Win Forms for a while, you will see that it is a much easier to code, cleaner, more object-oriented, and more complete implementation of the Windows GUI.