Just in case you missed it, Silverlight 2.0 RC0 can be installed on Visual Web Developer 2008 Express Edition SP1 ! which, by the way, neither Adobe Flash nor Adobe AIR have ( a free development environment , which is NOT limited in time and functionality )
On April 26, Adobe announced strategic plans to move the development of Flex to an open source model. It seems that competition is always a good thing, remember yosi 's article on a similar case: Microsoft/Google .
Due to the fact that i'm NOT a Flash Developer I can't agree or disagree, but this is something to think about http://blogs.zdnet.com/Stewart/?p=351