Get-LocalGroup.ps1

function Get-LocalGroup {
# PS C:\Users\IEUser\Desktop> Get-LocalGroup -GroupName Administrators
#
# AccountName   AccountSID
# -----------   ----------
# Administrator S-1-5-21-1116692041-1164204812-2329106322-500
# IEUser        S-1-5-21-1116692041-1164204812-2329106322-1000
# sshd_server   S-1-5-21-1116692041-1164204812-2329106322-1002

    param(
        [String]$GroupName
    )

    # Result array
    $UserArray = @()

    # Fubar WMI Query
    (Get-WMIObject win32_group -filter "LocalAccount='True'" -ComputerName $env:COMPUTERNAME | Where-Object {
        $_.Name -eq $GroupName
    } | select @{
        Name="Members";Expression={$_.GetRelated("win32_useraccount").Name}
    }).Members | foreach {
        $HashTable = @{
            AccountName = $_
            AccountSID = (New-Object System.Security.Principal.NTAccount($_)).Translate([System.Security.Principal.SecurityIdentifier]).Value
        }
        $Object = New-Object PSObject -Property $HashTable
        $UserArray += $Object
    }

    # Print array
    $UserArray |Format-Table -AutoSize
}