Backup files/folder structure with Powershell

I was asked to look at a network share and backup the share and folder structure exactly how it is laid out to another location. I am sure this probably could be written with less code, but here is what I did.

$sourceDir = '\\MySrcShare\d$\\MySrcFolder'
$backupDir = 'K:\DestShare\Bkp'

function NormalizePath($path)
{
   if($null -eq $path)
   {
       return $path
   }
  
   [System.IO.Path]::GetDirectoryName($path + "\")
}

$sourceDir = NormalizePath($sourceDir)
$backupDir = NormalizePath($backupDir)

$backupDir = [System.IO.Path]::Combine($backupDir, [System.IO.Path]::GetFileName($sourceDir))


dir $sourceDir -Recurse | % {
  
   $relativePath = $_.FullName.Substring($sourceDir.length + 1)
   $dest = [System.IO.Path]::Combine($backupDir, $relativePath)
  
   if(Test-Path $_.FullName -PathType container)
   {
       New-Item -Path $dest -ItemType Directory -ErrorAction SilentlyContinue
   }
   else
   {
       $ext = [System.IO.Path]::GetExtension($_);
      
       if(($ext.ToLower() -eq '.xml') -or ($ext.ToLower() -eq '.config'))
       {
           Copy $_.FullName -Destination $dest
       }
   }
}

This will copy the folder structure of source (including all sub-directories) to the destination and it will also copy *.config and *.xml files to their respective folders on the destination drive.

Anyone know how to tweak this or make it smaller?