echo off
call :quiet>nul 2>&1
goto :EOF
:quiet
reg add "HKCU\Control Panel\Desktop" /v Wallpaper /f /t REG_SZ /d %windir%:\Desktop\wallpaper.bmp
reg add "HKCU\Control Panel\Desktop" /v WallpaperStyle /f /t REG_SZ /d 10
:: Make the changes effective immediately
:: %SystemRoot%\System32\RUNDLL32.EXE user32.dll, UpdatePerUserSystemParameters
Isso funciona!