Total: $755 Canadian Dollar
Roughly $5813.5 HK Dollar
I believe things in HK are much cheaper than Canada, so it's pretty much within your range. And the Motherboard has 2 PCIe port, so in the future u can just get another HD3870 and make a CrossFire setup. 500W should be enough to support 2 Graphic card and your CPU, WITHOUT overclocking. Oh, by the way the HD3870 will be well over 10,000 in 3Dmark06, and Crossfire is around 18,000.
good luck with your new PC !