i have a firewall but on rare occasions i use it... i mainly have it turned off. and i hate 3rd party programs because they have trojans most of the time...
Well, first of all, since you have experimented with some viruses, you know how damaging they can be. Because of this, I would *always* have a firewall and an updated virus scanner enabled on your computer. The virus scanner will help protect you from viruses while the firewall will limit the ability of any Trojans you have on your system from accessing the Internet.

As for third-party programs containing Trojans, what third-party programs are you referring to? In the last 10 years, I have been hit with one virus and one Trojan. The virus was from a web site (it was the Nimda virus and Symantec hadn't released definitions for it yet, and one of the webservers I administered was hit with it). The Trojan was through an e-mail, once again, I got it before Symantec had released definitions for it. When it asked for Internet access, I immediately blocked it, and sandboxed it until the definitions were released to remove it.

AJ