Graphical and Audio logon for individual users ?

Ok So skinning XP or any MS O.S. is pretty simple. What i am looking for is basically the ability to run a 6 second mpeg or avi(in full screen) with the audio greeting of ” Welcome (insert user name here) the time is now (insert time here)” Just how possible is this? and what ways could i go about it? I am researching but it seems not many people do this. Wondering if just editing resource files and redirecting certain files to what I want. The big issue is getting it to load before the user has access to the GUI. and Having it start immediately after successful password entry. All systems are on local login. With with NAT, so its pretty much all p2p wired.