You can use this one-liner to get a list of VMs with their configured and running Guest OS:

Get-VM | Sort | Get-View -Property @("Name", "Config.GuestFullName", "Guest.GuestFullName") | Select -Property Name, @{N="Configured OS";E={$_.Config.GuestFullName}},  @{N="Running OS";E={$_.Guest.GuestFullName}} | Format-Table -AutoSize