Windows 7 (64-bit) or Windows Server 2008 R2 (64-bit). KB Number: KB976932 .
The identifier appears to be a specific build signature or a unique file hash (likely MD5 or SHA-1) associated with a Windows 7 Service Pack 1 (SP1) 64-bit update package. Windows 7 (64-bit) or Windows Server 2008 R2 (64-bit)