Forefront Client Security v1 and how it relates to MOM 2005

FCS uses the MOM infrastructure for event and alert gathering. The version of MOM 2005 included with Forefront Client Security is stripped down and customized quite a bit during the installation of the collection server role. This is part of the reason why you cannot use your existing MOM 2005 infrastructure for FCS v1.

A few important notes:
1. If you have an existing MOM infrastructure, you cannot use it for FCS. Your existing MOM infrastructure and FCS's use of MOM are completely separate.

2. If you do have MOM, you cannot share the One Point (Operations DB) or SystemCenterReporting (Data warehouse DB) with FCS. The two pairs of DB's must always remain separate!

3. If you have an existing MOM infrastructure, you can still monitor those machines using FCS (MOM supports multi-homing the agents).

It may be easier to not think about MOM as a separate prerequisite (like SQL), as the FCS setup handles all the MOM configuration details. If you already have MOM, just remember that you can't use it for FCS and if you don't have MOM, you don't have to worry about installing it, as the setup handles that for you.

Originally gleamed from here, with some of my own notes added.