A littile while ago I wrote about the release of Vista RC1. I loaded the RC right after it was released and it has been operating flawlessly for me since then.
I wanted to point out that the RC1 release of Vista has the release candidate for .Net 3.0.
I have been doing a bunch of work (mostly with WPF) and it is working 'like a champ'.
If you wish to do some development work on .Net 3.0 with the RC I would recommend you pick up the Orcas CTP for .NET Framework 3.0 RC including Cider. Here's the direct link.