Quite frankly, you did a good job for this budget. It is hard to do better than this at only $600 AUD. However, the small increase in price can sometimes yield substantial increase in performance. If that's OK with you, I can suggest something like this:
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Pentium G4560 3.5GHz Dual-Core Processor ($78.00 @ Umart)
Motherboard: ASRock H110M-HDS Micro ATX LGA1151 Motherboard ($75.00 @ Umart)
Memory: Crucial 8GB (1 x 8GB) DDR4-2133 Memory ($58.00 @ Shopping Express)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($64.00 @ Shopping Express)
Video Card: Gigabyte GeForce GTX 1050 Ti 4GB Video Card ($229.00 @ PCCaseGear)
Case: Deepcool TESSERACT SW ATX Mid Tower Case ($55.00 @ Mwave Australia)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($89.00 @ PCCaseGear)
Wireless Network Adapter: TP-Link TL-WN781ND PCI-Express x1 802.11b/g/n Wi-Fi Adapter ($15.00 @ Shopping Express)
Total: $663.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-01-19 00:38 AEDT+1100
For roughly $60 AUD more, you get:
- a faster CPU for gaming (this little Pentium is virtually the same as Core i3, the differences are negligible, as it has 2 cores WITH hyperthreading). VERY IMPORTANT: before buying confirm with the seller that the motherboard contains the latest BIOS which is required for that Pentium to work (it is very new, came out very recently).
- the platform is upgradeable to Core i5/i7
- you have DDR4 memory (only a single stick so you can upgrade to 16GB later if needed by adding the identical one)
- much better power supply and faster graphics card.
I left out the optical drive, if you really need it then get it too, of course.