Hi Johno,
Welcome to CocoonTech! IMO, I would keep video security seperate from your HTPC. Your HTPC cpu/hd can get really busy either because you are recording several shows, or because you are recording your video cameras, and one will interfere with the other. You also might want to take a look at mHome, a MCE HA package, which will support cameras in the future (but only to watch feeds I am sure, doubt it can record the source). Life|Ware is another package, but seems to be targetted at installers (read: expensive), and I do not believe it is available yet.