Can't load a .NET type in PowerShell
Your new-object syntax is a little off. Try this:
[System.Reflection.Assembly]::LoadWithPartialName("System.DirectoryServices")$machine = new-object -typeName System.DirectoryServices.DirectoryEntry -argumentList "WinNT://localhost,computer"
There's no need to load anything. Use the adsi type accelerator:
[adsi]"WinNT://localhost,computer"
I think the syntax for New-Object is incorrect. Taken from [some documentation on New-Object]:1
New-Object System.DirectoryServices.DirectoryEntry("WinNT://localhost,computer")