As a sidenote, there is an upcoming TS certification for Forefront Client and Forefront Server (70-557) that will be soon out of beta. If you are familiar with the older Antigen products, and especially the newer rebranded versions for Exchange 2007 and Sharepoint 2007, you already have a headstart on that certification. As always, I highly recommend the premade VHDs that are available from Microsoft's website to get familiar with the whole product line.
Do not confuse Forefront Client Security and Windows OneCare - they are not the same. FCS is lightweight enough that I put it on my demo VHDs. OneCare tends to 'take over' too many aspects of the operating system for me to use on VHDs.
Another aspect of FCS that many people either do not know about or are misinformed about - you can run FCS on client machines without a 'home' server if you want. It makes it particularly useful when you don't need or want all the reporting services. It is just a matter of deploying the client with "clientsetup.exe /nomom".