Here are some free Windows Logon screen wallpapers/backgrounds I created a few years back. The Windows user logon boxes will fit nicely in the center to complement the images and goes well with the new Iron Man Windows 7 Start Menu Button I made. Instructions are available below the images on how to set them as your background.

            
Iron Man                            War Machine

Warning, this requires modifications to your Windows registry so only continue if you know what you are doing. If you don’t want to play with your register you could use a third-party tool like Tweak.com’s Logon Changer to make the change for you.

Step 1: Open the Windows Start menu and type “regedit” into the search bar and hit enter.

Step 2: Right click on HKEY_LOCAL_MACHINE and select Find.

Step 3: Search for OEMBackground, which should be in ComputerHKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionAuthenticationLogonUIBackground. If the key does not exist, add a new DWORD value with the name OEMBackground.

Step 4: Double click on the entry OEMBackground, and change the value from 0 to 1.

Step 5: Open Windows Explorer and go to the following path: %windir%system32oobe.

Step 6: Create a new folder named info, and open it.

Step 7: Create a new folder within info named backgrounds.

Step 8: Rename your desired wallpaper as backgroundDefault.jpg and place it inside the folder backgrounds (images must be less than 245KB in size).

Now just lock your PC, log off or reboot and enjoy.