I\'m using the auto-implemented properties syntax in the C# source files of my ASP.NET Web Application:
public int IdUser { get; set; } ... this.IdUser = 1;
Automatically implemented properties works in .NET 2.0, but you won't be able to compile code in Visual Studio 2005. There is a list of 3.0 features and their compatibility with 2.0
http://csharpindepth.com/Articles/Chapter1/Versions.aspx