I'm no expert on the subject, but from what I've heard .net is Microsofts answer to Java. Since Sun won and spanked Microsoft for modifying Java on Windows they decided to go a different route and try to force Java out of the market, by making everyone use there .net strategy. Other things that .net is doing is removing any Netscape style plugins from IE 6.0 and above. So that you'll have to use Microsoft plugins (ie. Quicktime wont work you'll have to use Microsoft Media Player).
The basic .net strategy is to turn the web into a more robust application service platform. They want to remove the obstacles that the web currently has (i.e. Stateless) so that it's easier to serve up applications. Ohh and easier to charge people monthly for software that they could only charge them for every time they bought the new version.
