With Windows 7, Microsoft has, for the first time ever, made it easy for end users and OEMs to change the Welcome Screen. Enabling this feature only requires a simple registry tweak and moving an image file to a certain directory on your computer:
1) Click Start, and in the Start Menu’s search box type REGEDIT and then press the ENTER key.
2) Find the following key:
HKLM\Software\Policies\Microsoft\Windows\System
Look for a DWORD value called UseOEMBackground. Make sure that it’s set to 1. If you don’t see it, right-click in the right pane and choose New > DWORD Value, name it UseOEMBackground and set it to 1.
3) Copy a jpg image to the following directory:
C:\Windows\System32\oobe\info\backgrounds\
Make sure that the file has the name backgroundDefault.jpg, is the same resolution as your monitor, and is less than 256KB.
No reboot is needed; in fact, once you’ve done the above tweak, you should be able to press CTRL+ALT+DEL to bring up the Welcome Screen and see your changes immediately. If you do something wrong, Windows will default to the standard Welcome Screen.
works on 7600 rtm