Vista Transactional File System
Transactional NTFS (abbreviated TxF) brings the concept of atomic transactions to the NTFS file system, allowing Windows application developers to write file output routines that are guaranteed to either completely succeed or completely fail. Transactional NTFS allows for files and directories to be created, renamed, and deleted atomically. Using transaction ensures correctness of operation; in a series of file operations (done as a transaction), the operation will be committed if all the operations succeed. In case of any failure, the entire operation will rollback and fail.
more here
http://channel9.msdn.com/Showpost.aspx?postid=142120
http://en.wikipedia.org/wiki/Transactional_NTFS#Transactional_NTFS
have some nuggets
http://www.microsoft.com/uk/msdn/nuggets/nugget/69/Programming-the-Transactional-File-System.aspx
Cheers,
Nasir Ali Khan