We are in the process of upgrading our domain environment from Windows 200, to Windows 2008 R2 (sigh of relief). When the upgrade is completed, we would like to move to using GPO software deployment.
The question I has is regarding how to manage moving hundreds of machines that have all had software manually installed, into GPO deployment. Will the software try and re-install? Will the client extension detect that they software is installed, and not attempt to re-install?
You can decide what action takes place inside the GPO settings. You can even set the GPO to remove the software if the policy is no longer active. My advice would be to test heavily using gpresult and then slowly roll your GPOs out. Remember you're going to see quite a bit of network traffic once the settings take place initially. I'd expect 50-70% success, expect to do a lot of manual troubleshooting on machines to see why the policy did not take effect.
Case in point: It's not as smooth sailing as MS would like you to think.