I am not going to pretend that I am expert enough in J2EE and .Net to say which is better.  Having talked to people who are experts in these areas (aka Ted Neward) I don’t think anyone is foolish enough to say one is better than another.  I do not want to start a new religious crusade.  I will say this “Without data you are just another person with an opinion.”  Show me the data!

Eweek has released some reports on Open Source vs. .Net stacks.  The results are surprising the JBoss on Windows outperformed JBoss on Linux (and everything else)!  Also the WAMP (Windows 2003, Apache, My SQL & PHP) came in 3rd.  If you do not believe the outcomes of eweek, this is just another point on a long building graph of studies:

Web Services Performance: Comparing Comparing Java 2TM Enterprise Edition (J2EE platform) and the Microsoft .NET Framework

Middleware Company Application Server Performance Case Study: Microsoft .NET Performance and Scalability vs. J2EE Application Servers 

Implementing Sun's Java Pet Store Blueprint J2EE Application using Microsoft.NET

Building XML-based Web Services in Visual Studio .NET vs. IBM Websphere Studio Application Developer

Microsoft .NET vs. Sun J2EE:  Nile Application Benchmark Results

Microsoft .NET vs. IBM Websphere 4.0 Benchmark Kit

All of these studies show Windows and .Net as better performing.  Some are sponsored by Microsoft, some not.  What is clear is that neither of these stacks are going away.  We definitely need to interoperate better! 

I love Eweek’s comment, “Probably most surprising was the solid performance that came from the stacks that contained a mix of a Windows server and open-source components.”  I could have told them that a few years ago!  Maybe I should send them a copy of my book!!!