Disclaimer Splash Screen

well if your network is domain based, try this. start,control panel, administrative tools, domain security policy, local policies,security options, message text for user attempting to log on AND message Title for users attempting to log on. Define the policy by adding in the test and click ok. repeat for the Title policy.

OR you can define the message text and message title it in Group Policy. click start, run, type mmc in the run box click go. click on the console radio button and choose ADD. Scroll down the list and find default group policy. Click Add in the add stand alone snap-in. Choose browse, domain controller and choose a domain controller. click finish. with the default domain group policy MMC snap-in open expand computers, expand windows settings, expand security settings, expand local policies,click on security options. Choose message test for users attempting to log on AND message Title for users attempting to log on.

There ya go

Now if you want a different splash screen to show than the Windows XP/2000 splash screen [you make your own] thats a whole other process. Let us know if you want to change the splash screen.

If you don't want to use policies, simply change the registry with a logon script. Here's the Reg Key to modify...
http://www.winguides.com/registry/display.php/22/