MattDamonisdumb said:
I am currently using Avira AntiVir Personal and I use Comodo Firewall with Defense+ (HIPS)

Should I also use this Threat Fire in conjunction with those first two, or is it overkill?

Thanks
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As you can see there are many opinions. For me the question is does Threatfire add any real value? I've tried it many times over the years and it has never proven useful. By that I mean it has never successfully either prevented or removed an infection. On the other hand it has occasionally caused serious system slowdowns and quarantined legitimate system files - such as Explorer.exe - which prevented the computer from booting. I haven't used it recently so can't comment specifically on the latest version. I'm sorry to offer such a negative review. It's anecdotal of course, but it has been my honest experience. YMMV