I found a little light reading entitled
"Java Succumbing to .NET in my Organization" by Neil Chaudhuri in which a local Federal Government contractor is moving towards .NET. If you really want to hear arguments on both sides of the aisle, this is it! Talk about light reading...
As for me, I prefer .NET technologies which is why I'm starting with Microsoft in about a week. I make no qualms about being an advocate for Microsoft products including .NET, BizTalk, SharePoint, etc. I've done both and I easily agree with Neil's assesment that Microsoft has made great strides with Visual Studio 2005 to include such products as FXCop, integrated unit testing tools, MSBuild, etc.