static extern bool SystemParametersInfo(SPI uiAction, uint uiParam, ref T pvParam, SPIF fWinIni); // T = any type

static extern bool SystemParametersInfo(SPI uiAction, uint uiParam, IntPtr pvParam, SPIF fWinIni);

static extern bool SystemParametersInfo(uint uiAction, uint uiParam, String pvParam, SPIF fWinIni);

static extern bool SystemParametersInfo(uint uiAction, uint uiParam, StringBuilder pvParam, SPIF fWinIni);

static extern bool SystemParametersInfo(SPI uiAction, uint uiParam, ref ANIMATIONINFO pvParam, SPIF fWinIni);

SPI, SPIF, ANIMATIONINFO

    private static UInt32 SPIF_UPDATEINIFILE = 0x1;

        SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, filename, SPIF_UPDATEINIFILE);

Const SPIF_UpdateIni As Integer = 1

Const SPIF_SendIniChange As Integer = 2

Const SPIF_UpdateAndSend As Integer = SPIF_UpdateIni Or SPIF_SendIniChange '3

intReturn = SystemParametersInfo(SPI.SetWallpaper, 0, strFile, SPIF.UpdateAndSend)

    static extern bool SystemParametersInfo(uint uiAction, uint uiParam, StringBuilder pvParam, SPIF fWinIni);

        if (!SystemParametersInfo(SPI_GETDESKWALLPAPER, (uint)sb.Capacity, sb, SPIF.None))

    public const int ERROR_IPSEC_IKE_GETSPIFAIL = 0x00003621;

        public const int ERROR_IPSEC_IKE_GETSPIFAIL = 13857;

      /// When using this option, the fWinIni parameter must be set to SPIF_SENDWININICHANGE | SPIF_UPDATEINIFILE; otherwise,

      /// When using this option, the fWinIni parameter must be set to SPIF_SENDWININICHANGE | SPIF_UPDATEINIFILE; otherwise,

public enum SPIF

    SPIF_UPDATEINIFILE = 0x01,

    SPIF_SENDCHANGE = 0x02,

    /// <summary>Same as SPIF_SENDCHANGE.</summary>

    SPIF_SENDWININICHANGE = 0x02

Enum SPIF

   SPIF_UPDATEINIFILE =    &H1  ' Writes the new system-wide parameter setting to the user profile.

   SPIF_SENDCHANGE =       &H2  ' Broadcasts the WM_SETTINGCHANGE message after updating the user profile.

   SPIF_SENDWININICHANGE = &H2  ' Same as SPIF_SENDCHANGE.