I'm having problems getting this usercentric part of SCCM 2012 SP1 working for me.

What I want to accomplish is to advertise MS Lync to a user group that's given access to Lync, let's call them Lync_Users. But I don't want the application to install if the users already have Lync (Most of them already do, this is mostly for new people added to the group).

So how can I create a collection for the Lync_Users group where the computer does not have Lync?

I was thinking of creating a collection of machines that do not have Lync. Then creating a new collection, limiting the collection to computers without Lync and adding the user group to that collection. But that seems like a lot and something that should be able to be put together with a query.

Create a Config Mgr "Application" for Lync and deploy it to a user collection of your Lync Users - Required Install.

Config Mgr will analyse each of the user's computers and if it detects Lync nothing will happen. If it does not detect Lync it will be installed. Furthermore if a user uninstalls Lync Config Mgr will reinstall it.