priviledge escalation techniques

Hi List,

I have been asked to test the network security of my organisation from
an internal perspective. My boss has not been particularly specific in
his requirements (other than asking that I don't break any operational
infrastructure) so I can approach the problem from whichever way I
deem most appropriate.

I suspect the first thing I will attempt is privilege escalation
techniques from a workstation with a domain user account to see if I
can install my own software/toolset. Can anyone suggest any good
whitepapers or tools that I can use to get a head start?

I intend to follow this up by scanning/targeting critical parts of our
infrastructure - domain controllers, mail servers, routers etc.
However, I am interested to know what other people would do when given
free reign to identify internal weaknesses - so how should I approach
this? This is not an 'audit' exercise, as I will not be given access
to server/infrastructure configurations.

Any advise on this appreciated.

Dan