Microsoft has released both the x86 and x64 platforms of Windows Vista 5381 today. This has surprised many people because this build was expected to be released as Beta 2 in the middle of May. This might mean that the build 5421 will get designated as Beta 2.
You have to be a Microsoft Connect user in order to download this build. The 32bit DVD is 2,296.55 MB and the 64bit DVD is 4,834.25 MB.