You got to love this delicious alpha feeling, when you try to install something and it fails with an non-understandable error message... Yum!!
In my case, installing Orcas fails. I managed to find out that the package responsible for the failure is the .NET 3.5 redistributable. While the error code is just a generic "error 1603", looking in the Windows Event Viewer shows that "Product: Microsoft .NET Framework 3.5 (Pre-Release Version) -- You must first install Microsoft .NET Framework 2.0SP1 before installing or repairing this product.".
So now's the question: Where do I find .NET framework 2.0SP1???
(background info: I am using Windows XP SP2, with .NET 1.0, .NET 1.1 and .NET 3.0 installed, including the whole WPF development environment)
(by the way, I posted a question about that on MSDN)