Windows

Try loggedon2 from Assarbad at http://assarbad.net/stuff/loggedon2.zip

It will show everybody logged on to your domain and which pc they are logged on from.

could you make a custom log or trigger emails on login of this user from the security event log on the domain controller?
i bet this is a report that is built into ad...

Download PsLoggedOn. I quote:

PsLoggedOn is an applet that displays both the locally logged on users and users logged on via resources for either the
local computer, or a remote one. If you specify a user name instead of a computer,
PsLoggedOn searches the computers in the network neighborhood and tells you if the user is currently logged on.

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 PsLoggedOn 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.

Just copy PsLoggedOn onto your executable path, and type psloggedon.

http://www.jsifaq.com/SUBJ/tip4700/rh4712.htm
this address has the download

From any windows xp or above computer joined to the active directory domain, type the following from a command prompt. And yes, you need the quotes or it won't work.

net view | find "username"