PC TimeWatch distinguishes between users by their login name. Although PC TimeWatch can work in all modes, it is strongly recommended that you enable session login and user profiles on your PC, preferably before installing. Otherwise, you'll not be able to differentiate time allowances between users and PC TimeWatch will run in a less secure environment. Also, in "no login" mode, the risk of getting a locked down system is high. You would have to boot the system in safe mode to recover.
To enable session login and user profiles, use the Passwords applet in the Windows Control Panel. Click on the User Profiles tab and select Users can customize their preferences and desktop settings.... Check the two options in the User profile settings panel (Include desktop icons... and especially Include Start menu...).
If you haven't created separate usernames for each person who will be monitored by PC TimeWatch, you should do so now, before continuing with PC TimeWatch. To create usernames, open the Users applet in Control Panel and select Add User. You should assign passwords to each username to prevent users from logging into each other's accounts. Also, when creating a new user, you should select the default Create copies of the current items and their content option in the Personalized Items Settings dialog box.
Windows may ask you to reboot after creating the usernames, but don't do so yet. There is one other setting you need to check. Open the Network applet in Control Panel, and make sure that the Primary Network Logon is set to Windows Logon and not Client for Microsoft Networks. A security flaw in the Client for Microsoft Networks option makes it possible to log on under another user's identity without entering a password. After making sure that the Primary Network Logon is set to Windows Logon, you can reboot your computer.
Under Windows 98 and Windows Millennium you just can't prevent a user from tampering with the system time. However, if you set the system date and time to a correct value before installing, PC TimeWatch will be able to detect changes and it will try to correct them. If you have a connection to the Internet, even a non permanent one, PC TimeWatch will try to update date and time from the Internet.