when you power up your Windows XP/vista computer,you will see the Windows XP/vista welcome screen probably.Are you want to use windows 7 Logon Wallpaper instead of XP/vista's?I talk you how to Change it.
First you should download the windows 7 Logon image or picture as long as it is a .jpg or .bmp
Second,Adding the windows 7 Logon Wallpaper.To do this follow the directions below:
1) Click on "star menu"-->"run".Type in "regedit",and press Enter to open the registry editor.
2) And you Navigate to:
HKEY USERS\ .DEFAULT\Control Panel\Desktop
3) On the right side Find the wallpaper value and double click
Then type in the full path of the image.Such as "C:\WINDOWS\System32\win7logon.jpg"
4) set "TileWallPaper" value to 1.Also set "WallPaperStyle" to 2.
5) Close all the things.
The next time you reboot your computer, the changes will take place.