I had no idea that prices in New Zealand were so bad...Americans really do have it lucky as we could build that same system for 700 New Zealand dollars here. We had a guy from Australia buy parts in America and then his aunt shipped them over to there becuase it saved it him A LOT of money.
regardless if you are looking to play a new game at very high frames you will need a faster processor such as a Core 2 Duo or AMD X2. And understand with a monitor that big your going to need something like an ATI X1950XT or better.