Is it Possible to Tell?

[GrumbleDook]

Speak with Finance ... Purchase orders are your friend.

[SYNACK]

There is a join date time stamp in active directory that can tell you when that machine account was created in AD. Could help if it has not been reinstalled and rejoined to AD.

You would want to use ADSI edit and have a look through the properties of the computer object. Could also work even if you have reinstalled but left the original computer object in AD.

[elsiegee40]

If you have WSUS, you can look at the time it last reported it's status to WSUS. It's not infallible and useless the next day, but it'll give you a clue.