using free software to protect computer, antivirus + 2 firewalls?

Hello everyone!

I am trying to protect my computer for free. Here’s what I have:

-avast free home edition
-free ad-aware edition
-windows firewall
-finjan internet searcher
-free pc tools firewall plus

Is this a good combination? Are there any problems with having this combo? How good is my protection?

Thank you all for your expertise!

Have a wonderful weekend.