It's well known that Microsoft is prepping a service pack for Windows 7, and now it appears an RC version has leaked to the web. The current build weighs in at a hefty 353 MB and is currently making its rounds on your favorite torrent site. Microsoft is expected to release a SP1 build this week at PDC 2010 on October 28th. Just with any service pack, Windows 7 SP1 will contain all previous fixes and patches rolled up into one update, as well as bug and security fixes that are still currently being tested.
According to Wzor, the leaked Windows 7 service pack comes in at Build 6.1.7601.17105.100929-1730, which indicates that the release was blessed by Microsoft on September 29th, almost a month ago. This age could also indicate that there are possible revisions to the release that is currently circulating.
Wzor has an incredible track record for these types of things, its probably safe to say that this is the real deal. However, as with any leak, install at your own risk as this is not an official release by Microsoft and depending on who you download it from, the file could have been altered.
Again, This is a Release Candidate software, install at your own risk!