I was surprised at how much the additions to C# 3.0 have changed (and improved) the C# language. Yes, C# 3.0 is backward-compatible, so older C# programs will still work, but using LINQ and the other new features can make a big difference in your new code. It's worth learning the new material. I currently have four books from O'Reilly that cover C# 3.0, including LINQ, lambda expressions, extension methods, impl I was surprised at how much the additions to C# 3.0 have changed (and improved) the C# language. Yes, C# 3.0 is backward-compatible, so older C# programs will still work, but using LINQ and the other new features can make a big difference in your new code. It’s worth learning the new material.I currently have four books from O’Reilly that cover C# 3.0, including LINQ, lambda expressions, extension methods, implicitly typed variables, and more. Here’s a quick listing for each of them:Programming C# 3.0 , Fifth EditionThis thoroughly updated tutorial for beginning to intermediate programmers covers C# 3.0 and the newest .NET platform for developing Windows and web applications. Now in its fifth edition… C# 3.0 Design PatternsWant to speed up the development of your .NET applications? Tackle common programming problems with C# design patterns. This guide explains what design patterns are and why they’re used…C# 3.0 Cookbook , Third EditionCompletely updated for C# 3.0 and the .NET 3.5 platform, the new edition of this bestseller offers more than 250 code recipes to common and not-so-common problems…Head First C#Head First C# is a complete learning experience for object-oriented programming, C#, and the Visual Studio IDE. Built for your brain, this book covers Visual C# 2008, Visual Studio 2008,… I’m told that C# 3.0 in a Nutshell , Third Edition covers LINQ in more detail than Programming C# 3.0 , Fifth Edition, but I don’t yet have a copy of the Nutshell book. Software Development