The .NET is better then the JVM because it was designed to run on windows only, so no run anywhere stuff needed to be designed.
I was doing Win32 development for 5 years and concluded the .NET development is the best way to go (Only if you can convince the marketing guy to include the 20MB runtime installer in the package)
Silverlight 2.0 runs C# code (any MSIL compiled code, really) on OS X quite well... It also includes a significant portion of the base class libraries.
