Putting this here mainly for my own benefit, but it may help others. If you want to find out which NT users are connected to your MS SQL (2005 or 2008) server, and which computer they’re using – simply use this query (which you could run in SQL Server Management Studio):
select hostname,nt_username from sys.sysprocesses
For added excitement, if you do use Management Studio, you can display the result as text or a grid to take into Excel and filter it.