Hey! You can create a banner that will come up just before you logon to the computer:

Start Regedit

Go to HKeyLocalMachine \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Win Logon

Create a new string value called LegalNoticeCaption and give it a value you want to see in the menu bar

Create a new string value called LegalNoticeText and give it a value you want to see in the dialog box

Now before anyone logs into that computer, this banner will come up on the screen.
This can be useful for any legal warnings you want to give regarding the use of the computer.