param (
	[VMware.VimAutomation.Client20.DatastoreImpl[]] $Datastore = ( Get-Datastore ),
	[VMware.VimAutomation.Client20.FolderImpl] $Folder = ( 
		Get-Folder "Discovered Virtual Machine" 
	)
)

function GetAllVmxFiles ( $ds ) {
	$DsDrive = $datastore | ForEach-Object {
		New-PSDrive -name ($_.Name) -psProvider VimDatastore -root / -datastore $_ 
	}
	$VmxFileInfo = $DsDrive | ForEach-Object {
		Write-Progress "Scanning datastores" "$_..."
		dir "$($_):" -recurse -include *.vmx # took 9 min!
	}
	$DsDrive | Remove-PSDrive
	$VmxFileInfo | ForEach-Object { $_.DatastoreFullPath }
}
function GetRegisteredVmxFiles { 
	Get-VM | Get-View | ForEach-Object { $_.Config.Files.VmPathName }
}

$AllVmx = GetAllVmxFiles $datastore
$RegisteredVmx = GetRegisteredVmxFiles
$UnRegisteredVmx = $AllVmx | Where-Object { $RegisteredVmx -notcontains $_ }

while ( $Answer -notmatch "a|[1-$( $UnRegisteredVmx.Length )]" ) {
	for ( $i = 1; $i -le $UnRegisteredVmx.Length; $i++ ) {
		Write-Host "[$i]:" $UnRegisteredVmx[$i]
	}
	$Answer = Read-Host "Enter the VM number to register it in VI, or 'A' to register all."
}
Write-Host "You answered $Answer"