Create Your Own Logon Message:

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

2 In The registry editor, drill down to the following key:
HKEY_LOCAL_MACHINE\software\Microsoft\Windows NT\Current version\Winlogon.

3 Right click LegalNoticeCaption,
click modify,
Type: THIS IS NEXT TRICK,and then click ok!

4 Right click legalNoticeText,
click modify, and then Close your message!

5 Restart Your Computer.

6 The message will appear every time you logon!