Microsoft Pre-release Software Visual Studio 2010 and .NET Framework 4.0 Community Technology Preview (CTP)

"Microsoft Visual Studio 2010 and the .NET Framework 4.0 are the next generation development tools and platform for Windows Vista, the 2007 Office System, and the Web."

You can download the virtual machine of the CTP here. You will need Virtual PC 2007 SP1 and 75GB available HDD space.