Is there a script or batch file to automate the log-on process from the XP Welcome screen? As all details are the same Username, Password, and Domain in a room of 30 machines.

The reason I don't use Windows AutoAdminLogon is I only want to logon temporary at different times as a user to run such things as online test for a class of high school students without the students logging on individually first, also it would be useful for admin tasks if I can change/specify the user details.