zarman,
Welcome to TSG
Why do you think your behind a firewall?
I would say that if you have a older PC with Windows 95 and you just did a product recovery you don't have a firewall.
Why did you use the product recovery CD?
To test your PC go here and run the Shields UP! test.
http://grc.com/x/ne.dll?bh0bkyd2
It will let you know if a firewall is running or not.
A firewall is really needed today just being online. You can get ZoneAlarm for free and it is one of the best.
http://www.zonelabs.com/