Get-InstalledSilverlightVersion.ps1

param ([string]$ComputerName = '*')

begin {
    filter Check-Online {
      trap { continue }
      . {
          $timeout = 1000
          $obj = New-Object system.Net.NetworkInformation.Ping
          $result = $obj.Send($_, $timeout)
          if ($result.status -eq 'Success') { $_ }
      }
    }
}
end {
    $pcs = get-adcomputer -filter * | ? Name -like $ComputerName
    $pcs | % {
        $machinename = $_.Name
        if (-not ($machinename | Check-Online)) {
            new-object pscustomobject -Property @{
                ComputerName = $machinename;
                Version = 'offline'
            }
        } else {
            try {
                $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $MachineName)
                $regKey = $reg.OpenSubKey('SOFTWARE\Microsoft\Silverlight')
                $version = $regKey.GetValue('Version')
                new-object pscustomobject -Property @{
                    ComputerName = $machinename;
                    Version = [Version]$version;
                }
            } catch [UnauthorizedAccessException] {
                new-object pscustomobject -Property @{
                    ComputerName = $machinename;
                    Version = 'unauthorized';
                }
            }
        }
    }
}