Mike or anyone else for that matter: do you take any kind of precautions that you can recommend when going on IRC? Are modern consumer routers with enabled firewall suffice? I remember back in dial-up days script kiddies with little know-how could do really nasty and damaging things to one's system since then I stayed away from the IRC for the sake of not exposing my hostmask, network and system to all sorts of malicious probes. Is it safer nowadays?
IRC isn't the big danger, I consider it relatively safe, unless you consider people knowing your IP to be a risk and only if they have a reason to target you. Just knowing your IP address doesn't entice a hacker to target you at random if you're just joe anybody, but if they think you might have something they want, then it would be a risk. The biggest risk for the average home user behind a firewall is they browse to a website that serves them something that exploits a hole in their browser (aka "drive-by download") or in a plugin (such as Adobe Flash), or they download something that contains malware. A firewall can't stop any of that, because a firewall will let through any incoming responses to outbound requests - exactly what web surfing is. If it stopped such responses, you wouldn't be able to use a web browser.
Any site can get you - because sometimes the exploits come through the third party stuff (like banner ads) hosted on completely legitimate websites. As a rule, you're more likely to get hit on websites where you're looking for "something for nothing" (free porn, pirated software, the latest sex tape, etc.) where the site's existence is probably funded by the sleaziest advertising companies who turn a blind eye to exploits. And you are less likely to get hit on sites where security is a priority - such as your bank site. Antivirus helps protect against stale threats, but many exploits in the wild will not be detected by antivirus, a situation that will not change any time soon.
The only way to really protect yourself from that is to do all your normal web browsing on one computer that you don't care if it gets infected, or something that's easy to restore to its pre-infected condition (e.g. Live CD), and then do all your sensitive web browsing (banking, bitcoins etc) on another computer that you
never use to surf the web at large. Keeping your operating system up to date is also a prerequisite.