usage depends on what you're doing. If you're writing some type of framework code that will be used by VB or other .Net languages, you should use String as it is the actual .Net Framework type. If you're just using C#, then string is the better choice as it maps to String, but may also include additional methods or properties that don't exist in String.

>No, because C# distinguishes between string and String. I'm working hard at convincing myself that that is a good thing :).