These are leaked builds. They are not available on the website to Technet/MSDN or the general public. There is a rumor circulating that there will be a Release Candidate 2, but since retail availability is scheduled for October, this is unlikely. If anything, the RTM will be August or September indicating that these leaked builds are minor refinements before they reach a RTM build. There is also a seperate tree that they are using for Service Pack 1 which is already in development, indicating that the current version of Windows 7 (RC) is seen as stable enough for a commercial release. The Release Candidate is not supported by Microsoft so you should not expect to get updates via Windows Update, however some test updates have been published. It is unlikely any serious updates will be published via Windows Update until the commercial availability of the OS.