Here are some steps:1. Click start->Run->type Regedit and press enter2. Find the following registry keyHKLM\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background3. Now in right-side pane, set value of OEMBackground to 1.4. Put your custom image in %windir%\system32\oobe5. Create a new folder info and background within newly created info folderFor example: %windir%\System32\oobe\info\backgrounds6. Now you can copy or place your desired wallpaper to this background folder with file name backgroundDefault.jpg
Whoever posted this TYVM:) i lost this on a reformat.
If (like me) the OEMBackground entry isn't there you will need to create it yourself.
1. Click Start, type Regedit.exe and press ENTER:
HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \ CurrentVersion \ Authentication \ LogonUI \ Background
2. Create a new DWORD vayour lue named OEMBackground
3. Double-click OEMBackground and set 1 as its value data.
4. Exit the Registry Editor.
5. Download the image submitted here and place it into "C:\Windows\System32\oobe\info\backgrounds"
If "info\backgrounds" doesn't exist just make the folders manually.
You can actually use a 3rd party application that would do the change without editing registry entries or navigating to Windows folders. You can search for Windows Logon background changer. You can even add an entire folder of pictures.