This scrip will pull a list of all Windows VMs including their vCenter Name, FQDN & Guest OS Version. You can make it more tartget by specifying a Datacenter &/or a Cluster e.g Get-Datacenter DC Name | Get-Cluster Cluster | …

#Get Windows VMs inc FQDN & OS Version
get-vm | where {$_.ExtensionData.Guest.GuestFullName -Like "Microsoft*" -or $_.ExtensionData.Guest.GuestFullName -eq ""} | select Name, @{N="Tools Status";E={$_.ExtensionData.Guest.ToolsStatus}}, @{N="GuestHostname";E={$_.Guest.Hostname}}, @{N="GuestOS";E={$_.ExtensionData.Guest.GuestFullName}}