Best way to monitor a server with screenshots

One of our customers, the Managing Director of the company, has demanded us to give him the password of the administrator-account of his domain. No problem sofar.

Now we are having a few conflict which are caused by his playing around on one of the servers, we cannot proove this.

I am now looking for the best way to monitor this Windows 2003-server with screenshots so we have some evidence in hands and we can confront him with his own actions the next time things go wrong.

Kind regards,
MS