What follows is a how-to for installing Trac as a Windows service. The benefit of this is being able to log off of the server machine without stopping the tracd server.
The bulk of the information used to figure this out come from Microsoft's How To Create a User-Defined Service and a guide for Windows NT Tcl/Tk Server Installation.
The steps are actually pretty simple:
C:\Program Files\Resource Kit\Instsrv.exe Tracd C:\Program Files\Resource Kit\Srvany.exe
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tracd\Parameters]Application with the path to the tracd executable.AppParameters with the parameters you use to run tracd.AppDirectory with the path to the directory which contains the tracd executable.Now you should be able to log out and still access the Trac server.
Discussion
A much easier way to run Trac as a Windows service is to use WindowsServiceScript (http://trac-hacks.org/wiki/WindowsServiceScript), available at Trac Hacks.