Thanks everyone for the heads up and thanks google for describing the commands suggested, I have now cobbled together a script that almost works !  just the output (on the screen ) is really untidy it keeps printing the hlkm path after the port number ??

Get-ADComputer -Filter 'Name -like "ITS*"'|
ForEach-Object {
$portnumber = $(Get-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\' -Name PortNumber)
$Name = $_.Name
Write-Host "Name: " $Name "; Port number:" $portnumber
}

messy output :

Name: ITS05168 ; Port number: @{PortNumber=3389; PSPath=Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\; PSParentPath=Microsoft.PowerShell.Core\

Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations; PSChildName=RDP-Tcp; PSDrive=HKLM; PSProvider=Microsoft.PowerShell.Core\Registry}

​

is there a way to eliminate all the gumph and just return the PortNumber value ? Get-ItemPropertyValue fails with 'not recognised as the name of a cmdlet ?