Is Firewall necessary for home PCs? IF yes then which one?

I am thinking of installing Comodo Firewall or Zone Alarm. But I really want to know if one is really required on a home PC? I already have Threat Fire and AVG Free installed in my machine. Does Firewall protect against malware, Adware etc? Which Free licensed Firewall will be the best?

AVG free has lots of problems lately. I would uninstall it and then install the following programs.
Comodo has an internet security free. It is there firewall and anti virus

http://www.comodo.com/

This is a very good program, that completely runs in the background

http://www.comodo.com/boclean/boclean.html

http://www.pctools.com/firewall/

This is also a good firewall and it is free

Home Laser Hair Removal

Telikin Elite 20 Touchscreen Computer (1.6Hz Dual Core Processor, 2 GB RAM, 500 GB Hard Drive) $1,199.00 20″ Telikin Elite Easy to Use Touchscreen Computer for Seniors Easy to Use | Built-in Features | Safe & Secure: ** A COMPUTER FOR THE REST OF US ** Originally designed as worry-free easy to use computers for seniors & baby boomers, Telikins have grown to earn fans with the whole family – New user to tech savvy… young to young at heart. Today, Telikins are for anyone who wants the BENEFITS of…

Local PC Superhero – How To Make Easy Money By Helping Your Neighbors Rid Their PC Computers Of Those Nasty Viruses Finally, a legitimate, in-demand And PROVEN work at home business. Discover an easy to start, low overhead business with high earning potential, that actually does BETTER in a bad economy! This opportunity came knocking on my door (literally!). I’ll describe, in detail, the circumstances and coincidences that lead me to the adventure of becoming a Local PC Superhero. What exactly is this business?…