"Teamspeak2", often referred to as TS can be downloaded for free at http://www.goteamspeak.com/index.php?page=downloads
If you don't have it already, the version you will need is called 'TeamSpeak 2 Client' which is listed at the top of the page linked above. The filesize is only 5.59 MB to download, and has a simple .exe installer to get it setup on your computer.
Once installed, double click the icon to open up the main screen. Click 'Connect' and then 'Quick Connect' from the main menu at the top of the screen:
A dialogue box will appear.
In the 'Server address' box, enter teamspeak.inspire.net.nz
In the nickname box, enter your NZFFac username.
Leave the rest of the boxes blank and click 'connect'
Once logged on, you will appear in the 'lobby' of the Inspire TS server. Right click on the 'Flight Sims' title in the box on the left hand side and click 'Switch to channel'
Next, you will need to set up a 'push to talk key'. When ever this certain key is pushed, it activates your microphone and whatever you say will be heard by everyone else on the channel. When you have finished speaking, you let go.
To do this, go to 'Settings' menu and the top of the screen and click 'Sound Input/Output Settings'.
In 'Voice Send Method', select 'push to talk' then click on the 'Set' button and choose a key which you will press every time you wish to speak. A good key to use is 'Scroll Lock', as it has no assignment inside fs2004 and won't change anything in the sim when you press it.
Once you are ready to speak, leave TS running in the background open up flightsim and speak away!
If you need further help, please post your problem in a reply below. Cheers
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.. this is Australian "Fair whack diddle mate, a dingo ate your baby"... were here in the NZ we say "Right chaps toddle pip, off for a bit of flying" 
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