Ok - try going to AVG's website and see if you can download the latest version (dont actually do it thou - we just want to see if you can get there). Do that with windows update as well. Some bug's will block access to sites like these...
Re the firewalls - kill one of them. Personally I would just leave Windows firewall on. Running two can cause problems and you gain nothing from it.
You still haven't told me which browser...
But try going to the site in both browsers - let me know if the same thing happens on in both...
We are trying to nut out if the traffic is been stopped at your end or if the traffic is free flowing but there's some other problem at your end with rendering the page.
www.cairns.com.au does throw a javascript error - but this shouldn't stop the page loading...