[ Register or Signin to view external links. ]

That is the best I could do with your budget, not fond with the Australian dollar and the prices on components are a lot more than US dollars. That PC will handle games such as BF3 and Skyrim at high settings with at least 40-50 FPS. It also allows you to overclock the CPU to around 4.3Ghz which will improve the performance. You also have the latest generation of the Intel CPU in there so you won't need to upgrade for many years. The only upgrades I could recommend would be the Graphics card as I initially had a GTX 560 TI but had to downgrade to the 7770, which is still an excellent Graphics card. Overall, this PC will perform 10x better than what you initially had.

Edit: Also, the motherboard with the build supports CrossfireX, meaning you can install 2 Graphics cards at once to improve the performance when gaming. However, be aware that if you wish to do this in the future that you purchase a more powerful power supply as it will need more power to run both Graphics cards. Also, if you do wish to use this feature make sure that they are both AMD Graphics cards as it will not work with an AMD and Nvidia together. For example, you can buy another 7770 to benefit from this option.