[gyroscope4]

since when is a firewall expensive? there's one built into osx. just look in system preferences > sharing > firewall, and click "start." pretty cheap.
and "unpopularity" is hardly the only reason osx is more protected from virus attacks than windows, but there are lots of other threads with that discussion.

[Naphtali]

gyroscope4:
What exactly is a firewall?
Running (the more popular yet obsolescent) OS 9.2.2, does it also have this integral with OS? If yes, where do I find it? If no, what are my options?

[dcipjr]

No, only OS X has the Firewall. A firewall is a software (or hardware) device used to block access to ports on your Mac, providing protection from hackers.
Think of your Mac as a house. A firewall locks the "doors" of the house from the inside. People (data) from inside the house (your Mac) can get out, but people (data) from the outside (the rest of the Internet) can't get in, unless you let them in (unblocking ports).
OS X has a built-in firewall. Unix is a very secure OS, so OS X inherits a lot of that security and stability, including the free, industrial-strength firewall.
I'd highly recommend upgrading. OS 9 is becoming less and less popular. Apple doesn't maintain OS 9 anymore, so any security holes will stay. For the best security, I'd go X.
That being said, if you must stick with 9, you can purchase firewall software. If you have an OS 9 disc, there might be a demo of firewall software on the disc--several of my OS 9 software install discs have this demo.