Comodo Internet Security is a suite that incudes a Firewall, an Host Intrusion Prevention System and an AntiVirus and leverages on a Prevention/Detection/Cure approach to protect end-users againsts different types of threats including viruses and spywares, trojans and malwares.
The AV part of CIS focus on Detection and Cure and its fast-growing signature DB will statically detect viruses, trojans, keyloggers, spywares and also potentially unsafe apps.
In these early phases the AV component focus on realtime and manual scanning and has no POP3 shield ATM.
The realtime scanning wil detect know threats as soon a new executable is created (eg decompressing a zip file) or is launched.
The manual scanner will also detect threats in compressed archive (eg zip files)
The Firewall and HIPS components focus on Prevention and working along with a list of known safe apps will allow those trusted applications to operate and warn if an unknown app attempt an internet connection or try to access a protected resource.
As for 3rd party AV/Antispyware products like Spyware Terminator there should be no issue as long these products don’t provide systemwide feature that can confilict with CIS.
Realtime scanning or HIPS will potentially cause issues. Anyway AFAIK it would be still possible to use Spyware Terminator in its basic configuration as a manual scanner (Disabling its HIPS or any other realtime feature).