Wanna tell your friends about the do's and dont's in your computer when they login in your absence. Well you can do it pretty easily by displaying a legal notice at system start up.

REGEDIT

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system]

"legalnoticecaption"="enter your notice caption"

"legalnoticetext"="enter your legal notice text"