Microsoft has made the Release Candidate of Avalon and Indigo Beta 1 available to the public. This version works with .NET 2.0 and Visual Studio 2.0 Beta 2 and only includes the assemblies.

Those looking to upgrade a prior version should execute the following command to remove the March CTP version before attempting to install the Beta 1 RC.

msiexec /x {C350D87C-7B67-43E2-B717-E9ADABE2F631}

The Beta 1 RC download will execute an install program that downloads the files from the Internet and installs the assemblies into the GAC. MSDN has been propagating the files to their servers and so the files have been intermittently available, but you should be able to download them here.