They work a lot differently than traditional AV solutions (they are technically IDS solutions, as they monitor your machine at the network layer and are capable of blocking threats directly at the network driver layer.)
That and they're both backed by their respective vendors better than any of the other AV solutions, as most of the fortune 500 companies rely on them to protect their data centers, etc.
Sounds very good! That's the way all security products should go. The traditional signature based scanning and simple port- or application based firewalls are just not enough these days.
-j.