Get the latest edition, covering .NET 4. The chapters on concurrency and I/O alone are worth the price of admission.
Personal Recommendation (after learning the language) http://www.amazon.com/CLR-Via-C-Pro-Developer/dp/0735621632
Second, I'd say that for a general book that's informative and not too hard to learn use Wrox's Professional C# 4 and .Net 4. I prefer Wrox books as they are usually the same format book to book and most have you complete a project to practice what you're learning: http://www.amazon.com/Professional-4-0-NET-Wrox-Programmer/d...
Depending on what you're using for your data store I'd also suggest reading up on ADO.NET 4 but I don't have any experience with books on that topic so perhaps someone can suggest some.
http://www.amazon.com/Framework-Design-Guidelines-Convention...