Bigpond don't block p2p. However of course like all Australian ISP's there's no unlimited download options, so if toward the end of the month you find your speed is slow as heck, you know you have gone over the limit & need to wait until the start of next month & refresh period when it's set back to zero.

Try shutting down your OSX firewall whilst LW is closed & then see if that helps. I just bought I new router & found the OSX firewall was clashing with the router's firmware. Different brand router to yours though. OH ... perhaps a reboot after closing down firewall may help though probably not necessary. ie: System Preferences -> Sharing -> Firewall (tab).

I don't have Port forward instructions for your OSX for your device. But it should be similar to those here Port Forwarding for the Motorola SBG 900

For setting up a static ip in OSX, see World of Warcraft Community Site -> Support -> OSX Static ip

Remember after doing this to save your settings in your router (some brands or models also require rebooting router to get the change into action.) And even rebooting your mac might be a good idea too. Remember setting up static ip is the first thing you must do BEFORE port forwarding otherwise it won't work. So if have Port Forward rules set up whilst using a dynamic ip, cancel them & re-do them AFTER having set up static ip. Perhaps it will be safer for you to re-do this if you were unsure about your first attempt. Note: the static ip quoted in the windows instructions may be different to the mac one.

I have more thoughts about the connection problem.

1. Mac OS X can connect THROUGH your firewall - mine is permanently switched on, and there times I can connect and times when I can't. The brick wall you see does not necessarily mean it's YOUR firewall - it might be a block your ISP has set up, which limewire has detected. For example, right now I am connected to limewire aok, and there is no wall showing, even though my OS X firewall is switched on.
Last week I tried an experiment - I set up a user account called Limewire and logged out of all other accounts. While in Limewire, I used my admin details to turn the firewall off. I then deleted all the limewire preferences and relaunched. I had to go through the setup procedure and when i got through that, the brick wall was there in limewire even though all my firewalls were switched off.
QED - the brick wall icon shows things outside of your computer as well as inside.

2. Until the last 2 days, I could only connect during the daytime, Monday to Friday. I was blocked evenings, weekends, and even on the Bank Holiday! This can only mean ISP blocking (tiscali in my case, and yes, I have read all the posts here about tiscali). But for some unknown reason, the last 36 hours I have been able to connect to limewire continuously.

3. The way I figure it is - if you have followed all the advice here, and you still have a problem, you may find it is your ISP. If you can still connect during the day, well it's better than nothing. If you cannot connect at all, ever, you may need to think about changing your ISP.

I turned off my firewall and rebooted but still nothing.

I clicked on the link you gave me for setting up a static IP and followed the instructions.

1. It says "select the adapter you use to connect to the internet (for most users, it will be the Built-in Ethernet adapter)... i selected airport because thats what i use.

2. My configure IPv4 field is set to Using DHCP. I wrote down my IP Address, Subnet Mask, Router but had nothing in the DNS Servers field.

3. I changed configure IPv4 to manually instead of Using DHCP and entered in the numbers i had written down.

i saved the settings and then my internet stopped working :S i put it back on using DHCP and it worked again. any clue what i should do? you've all been so helpful so far, i really appreciate it!

by the way, if those settings worked which one of those numbers would have been my static IP? IP adress right?