I have been using Comodo CIS since the start and it gets better and better. Very light on resources and no conflicts. In conjunction with SpywareBlaster in real time and SAS and MBAM as on demand scanners I get the occasional tracking cookie on my weekly scan gut haven't had a serious infection since using the above. To top it all CNET Downloads has just given Comodo CIS V3.9 a 5 starred review which is copied below. As Comodo is a free program I think the companies like Kaspersky etc must be getting worried about the success of Comodo.
Reviewed by: Seth Rosenblatt on June 22, 2009
Comodo has merged its antivirus program with Firewall Pro, creating a free security program that aims to be more to more people. Although this may frustrate some users who want only one program or the other, the installer does let you opt out of either of the components. Users are also asked to install the Comodo SafeSearch and Ask.com toolbars, so be careful if you tend to install on autopilot. CIS requires a reboot.
Resource management is better than before, with hogging all but eliminated. It provides a smorgasbord of information and options for advanced users, but it's simple enough for beginners, and runs smoothly and silently in the background. The version 3 interface utilizes a plain white color scheme and replaces old terminology with more intuitive terms such as Summary, Firewall, Defense, and Miscellaneous. In each, there are links to relevant security issues so users can drill down to learn more about how the firewall is performing. The firewall rears its head most often when Security Alerts ask about new Internet connections as the program "learns" your computer's behavior.
Shield-shaped buttons at the top facilitate switching between the antivirus and firewall modules, as well as a summary tab that provides a general overview. Users can toggle automatic scans of archives or downloads, scans on start-up, manage the quarantine, and schedule scans and definition file updates through a clean and comprehensible list of links. The definition file update crashed during its first use, but was stable thereafter. Scans completed at a reasonable speed, but were not blazingly fast.
A third pane, Defense+, provides more-advanced security options including locking down specific files from modification, perusing an active processes list, and protecting specific Registry keys. Comodo Internet Security's wide range of free services are generally good, but the firewall is clearly the strongest of the bunch.
Motherboard: Gigabyte GA-MA770T-UD3, CPU: AMD Athlon II X3 450 Processor, Memory: OCZ 4GB (2x2GB) DDR3 1333MHz,Graphics: PowerColor HD 5750 1GB GDDR5,
PSU: Corsair 430W CX PSU 4x SATA 1x PCI-E, Hard Drive:Samsung SpinPoint F3 500GB Hard Drive SATAII 7200rpm 16MB Cache.