Users found in a specific OU should always be a member of a specific security group

Here we have a very simple criteria:
Users found in a specific OU should always be a member of a specific security group.
This does not require any human input or modification. We just need a way to compare the users in the OU with the users in the group and make any necessary changes.

PowerShell

Windows Server 2008 R2 with Active Directory cmdlets:
$OU=”Organizational Unit distinguishedName”
$Group=” Group distinguishedName”

Get-ADGroupMember –Identity $Group | Where-Object {$_.distinguishedName –NotMatch $OU} | ForEach-Object {Remove-ADPrincipalGroupMembership –Identity $_ –MemberOf $Group –Confirm:$false}
Get-ADUser –SearchBase $OU –SearchScope OneLevel –LDAPFilter “(!memberOf=$Group)” | ForEach-Object {Add-ADPrincipalGroupMembership –Identity $_ –MemberOf $Group}