Jake,
Might I add that Get-Service is a PowerShell cmdlet. Get-WMIObject is not a PowerShell cmdlet. By running Get-WMIObject you’re utilizing another technology. My personal preference is Get-WMIObject.
Your environment might block WMI requests. You should try a simple query first against one remote machine.
get-wmiobject win32_service -ComputerName SomeRemoteComputer -Filter “Name = ‘wuauserv’”