Here are some firewalls for Vista that are free to use. If you are like me there are still programs out there that arent compatiable with Vista. A firewall is very important to have on your system especially with all the viruses and things out there that can get on your computer if not protected. Here are three firewalls that you can use on Vista:

Comodo Firewall Pro 3.0
PC Tools Firewall Plus 3.0
ZoneAlarm Firewall 7.1