http://blog.szynalski.com/2009/11/23/volum...system-restore/
... courtesy of this month's edition of Bruce Schneier's Crypto-Gram Newsletter.
That's a really good link marmite.
Thanks. Schneier's newsletter is worth subscribing to. As well as more general stuff there are always links to some really good articles on on all sorts of matters related to security and privacy, both in IT and the wider world.