Unless you are using something like cconnect on your network that info is not readily
available.
http://is-it-true.org/nt/atips/atips331.shtml -- Info on cconnect.
There is a free tool from SysInternals that may help called PsLoggedOn available in
the link below. --- Steve
http://www.sysinternals.com/ntw2k/freeware/psloggedon.shtml
PsLoggedOn's definition of a locally logged on user is one that has their profile
loaded into the Registry, so PsLoggedOn determines who is logged on by scanning the
keys under the HKEY_USERS key. For each key that has a name that is a user SID
(security Identifier), PsLoggedOn looks up the corresponding user name and displays
it. To determine who is logged onto a computer via resource shares, PsLoggedOn uses
the NetSessionEnum API. Note that LoggedOn will show you as logged on via resource
share to remote computers that you query because a logon is required for PsLoggedOn
to access the Registry of a remote system.