Thanks for your reply. The problem is that that motherboard costs about $290 NZD. That's quite a bit higher than our budget will allow.
I should also say that we are not looking at crossfire or anything like that. We'll be looking at only using one video card.
About your suggestion on using the 5000 series video card, we'll look into it more. Right now, we found a Sapphire Radeon HD5670 512MB in our price range. Is this a card that other people would recommend?