Windows XPe RDP save User Credentials

function Add-Credentials {
param(
    [parameter(mandatory=$true)][ValidateNotNullOrEmpty()][string]$Server,
    [parameter(mandatory=$true)][ValidateNotNullOrEmpty()][string]$Username,
    [parameter(mandatory=$true)][ValidateNotNullOrEmpty()][string]$Password
)

$code = @"  
[DllImport("Advapi32.dll", SetLastError=true, EntryPoint="CredWriteW", CharSet=CharSet.Unicode)]  
public static extern bool CredWrite([In] ref Credential userCredential, [In] UInt32 flags);

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct Credential
{
   public UInt32 flags;
   public UInt32 type;
   public IntPtr targetName;
   public IntPtr comment;
   public System.Runtime.InteropServices.ComTypes.FILETIME lastWritten;
   public UInt32 credentialBlobSize;
   public IntPtr credentialBlob;
   public UInt32 persist;
   public UInt32 attributeCount;
   public IntPtr Attributes;
   public IntPtr targetAlias;
   public IntPtr userName;
}

"@  
    Add-Type -MemberDefinition $code -Namespace "ADVAPI32" -Name 'Util'  
    $cred = New-Object ADVAPI32.Util+Credential
    $cred.flags = 0
    $cred.type = 2
    $cred.targetName = [System.Runtime.InteropServices.Marshal]::StringToCoTaskMemUni($Server)
    $cred.userName = [System.Runtime.InteropServices.Marshal]::StringToCoTaskMemUni($username)
    $cred.attributeCount = 0
    #Erhalten der Credentials: 1 = Session / 2 = Local Machine / 3 = Enterprise
    $cred.persist = 3
    $cred.credentialBlobSize = [System.Text.Encoding]::Unicode.GetBytes($Password).length
    $cred.credentialBlob = [System.Runtime.InteropServices.Marshal]::StringToCoTaskMemUni($Password)
    $result = [ADVAPI32.Util]::CredWrite([ref]$cred,0)
    return $result
}

Add-Credentials -Server 'Testserver' -Username 'DOMAIN\user123' -Password 'Passw0rd'