Which additional security programs are compatible with antivirus?

[deviddiya]

The terms for security programs can be a little overwhelming. I just want to know which additional programs I can use together with my antivirus. It would be good to have some kind of comprehensive guide to the available programs, but I haven't been able to find anything like that. I am only concerned with free programs. I have Avast. Is it compatible with:
Malware Bytes
Threatfire (does that contain antivirus itself, or not?)
Super Anti Spyware
And what about firewall? I don't have one specifically, as I was under the impression that Windows 7 includes a firewall. Is that correct?

[anon]

It would be good to have some kind of comprehensive guide to the available programs, but I haven't been able to find anything like that.

You don't have access to search engines?

[Appzalien]

A good antivirus is one that is active and running at startup. Other antiviruses and anti-malware will be OK if they are what's called "on demand". An on demand program like malwarebytes does not run at startup and will not interfere with your active antivirus. There is also the antivirus BitDefender 10 Free Edition which is an on demand antivirus you can use to double check your active one. Spybot Search and Destroy, Spyware Blaster, ASquared Free, Super Antispyware and others that are on demand are OK, but some AV's will complain about them. I haven't listened to the complains though, and have had no problems so far with multiple AV's and malware apps.