All sorted now, replaced all of the existing 80mm fans with new ones and added a 120mm to the side.
After this experience, would massively recommend Nexus fans, good flow rate and almost totally silent. Air cooling FTW!
One of my coworkers added a duct from his Home Air Conditioning and "Country Chrome" Duct Taped it to his case. Can you say "World of War Craft Addict" :o). Needles to say, he hasn't had any more heating problems.
Another thing, with all those fans and video cards, you might need a bigger power supply.