Create Your Own Logon Message

1 Click start
click run
type regedit,
then click ok!

2 Go to "Start>Run"  (OR)   press  "windows key + R"
type "registry" in the RUN.
In The registry editor, drill down to the following key:
HKEY_LOCAL_MACHINE > software > Microsoft > Windows NT > Current version > Winlogon.
click on "Winlogon"

3 Right click on "LegalNoticeCaption",
click modify,
Type: Your Heading (type whatever you want), and then click ok!

4 Right click on "legalNoticeText",
click modify, and then Type your message! (type whatever you want)

5 Restart Your Computer.

6 The message will appear every time you logon!