Just over a year ago I had a problem, I'd just bought a new PC and since it had 8Gb RAM it had to run 64bit Windows (see this post for an explanation on what that's all about). But 64 bit Windows doesn't support DOS based programs, now I'm happy for that to be the case as DOS is a very old technology and at some point I think that modern systems need to leave the past behind.
At Convallis we've been working with .Net 4 for some time and while WCF Data Services has been around (under a different name) since .Net 3.5 Sp1 we hadn't dabbled. However, while implementing a new feature for online ConvallisCRM which required a Silverlight component I decided to experiment with Data Services to provide the Web Services needed by the Silverlight component to exchange data with.
There is an awful lot of hype about Rich Internet Applications (RIA) at the moment, and it is one of the 'big' competitive battlegrounds between Adobe and Microsoft. I think that the RIA is one of the most exciting technologies in development at the moment and we'll start to see some rich web sites this year that go beyond Flash games or movies.