I need to force a password change and password rule change in a Windows 2008r2 environment

to force change passwords do this:

Highlight the users that you want to change
Right mouse button, properties
Account Tab
Check 'User must change password at next logon'

When you enable the password policy via GPO the users are not enforced by default. Meaning the passwords that they currently use will continue to work until it expires. When this happens they will then be enforced to enter a new password based on the new password policy.

Personally I would enable the policy and then just let the users passwords expire gracefully. This way it does not put a huge load on the PDC and also ensure passwords that were recently changed do not have to be changed again.

If you wish you can force users to change their password using the following commands...
Powershell
This command will change all passwords for all accounts that do not have the "password never expires" enabled

import-module activedirectory
Get-ADUser -filter * | set-aduser -ChangePasswordAtLogon:$true

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The command below is changing passwords based on OU location

import-module activedirectory
Get-ADUser -filter * -searchbase "ou=test,dc=domain,dc=com" | set-aduser -ChangePasswordAtLogon:$true

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You can also use dsquery | dsmod -mustchpwd yes to enforce change passwords as well. I personally like powershell as there is much more control and flexibility.

Will.