HI Bardlebee
A group policy is composed of a user component and a computer component, by default the easiest way to create a group policy is using the group policy management console or in the method you describe above ( which will start it, if its installed anyway)
My advise to you would be to ensure you are editing the correct section for the OU your assigning it to, make sure that the user section is completed if you have assigned it to a OU full of users....
On the client machine side there are a few things you can check
1) gpupdate /force - this will force the machine to pull an updated set of policies.
2) RSOP (
http://support.microsoft.com/kb/323276) this app will show, for a user or computer which policies are applied and what effect that will have.
As a start try those utilities and let us know how you go :)