Easty
Virgin Blue carry up to 20kg of sporting equiptment free of charge -perhaps a little more if you are lucky

They are generally pretty helpful...
Qantas are painful. I have had interesing experiences with them! Qantas use those packing crate things for luggage and freight on some planes - windsurfing gear can be too big for these and you can't get your gear on

You may then have to put your gear through with Australian Air Express (Qantas outsource freight to Australian Air Express). Australian Air Express want a lot of cash for their trouble and don't give a sh!t if you are on the plane or not. They don't guarantee freight (other than animals) will be on the same flight either

From my experience, if travelling within Oz with kit, fly Virgin and avoid the drama