Quality free Firewall programs?

I've had to reload my computer from scratch this weekend because of a particularly insidious virus (and the fact that in the past 4 years I never reformatted or reinstalled).
So, anyway, I am without a firewall at this point and was wondering if you all had any recommendations as to which of the available free-ware firewalls were worth getting.
Thanks for the help.
So, anyway, I am without a firewall at this point and was wondering if you all had any recommendations as to which of the available free-ware firewalls were worth getting.
Thanks for the help.