Hi Dan,
The only important thing to consider in this is that you do not have two resident anti-virus programs running together on one box. If you have one resident and another non-resident or one resident and several non-resident av or anti-malware solutions there is generally no conflict. There is an exeption to this rule of thumb by the name of Panda, because Panda signatures can be taken for malware by Avast, which is Panda's fault. I run avast together with ClamAV, TrendMicro RUBotted, and Comodo BoClean. Additionally I have SAS, and a-squared on demand and ewido micro on demand. Furthermore on a seperate USB stick I have the latest version of DrWebCureIt ready, also non-residental and a very fast additional scanner.
I think that is enough.
The answer on your question can be found here. Threatfire is a resident scanner, but non-signature dependant:
"ThreatFire 3.5 is a Antivirus Software product from threatfire.com, get 4 Stars SoftSea Rating, ThreatFire (formerly CyberHawk) provides behavior-based security monitoring to protect you from malicious programs such as Trojans, viruses, malware and other threats without relying on any signature updates. It can (should) be used along with your regular anti-virus software or firewall, adding an additional level of security to your system. The software works by continuously analyzing the behavior of processes and programs on your system and immediately alerts you if it detects any suspicious actions - you can then decide whether to allow or block the activity. ThreatFire comes ready-to-use and does not require any difficult configuration, however it also offers flexible rule settings that allow advanced users to customize the protection. The license of this antivirus & security software is Freeware, you can free download and free use this Antivirus & Security software."
So the answer to your question, Dan, my friend, is to be found above in italics,
Damian