What do you think of this i5 quad core gaming build?

That's really not that good. I know prices are high over there, but everything seems to be inflated by a good 50-75% over the exchange rate. I'd look at a different vendor. Regardless, there is a lot of silly expenses in there that is hurting the overall performance of the build.

Here's what you should change:

Case: Check out the Coolermaster 690, Antec 300, Antec 300 Illusion, Antec 900 (or 902), and the HAF 922. They should be cheaper (I know the first 3 definitely are), but even if they're not, they'll be close to the same price, yet overall better choices due to their higher quality. Using a cheaper case that will still fit your uses will free up the budget for parts that actually make a difference to performance.

PSU: A good brand, but I'd highly recommend picking up a 650W-750W unit, especially if you can afford a bigger GPU (which you should when I'm done)

Mobo: You can't beat the Asus P7P55D-E Pro. It's cheap, yet packed with features. It's also one of the highest quality boards out there.

RAM: That seems extremely expensive. Check some prices for other brands of RAM that run at 1600 mhz CAS Latency 7. EDIT: Now that I know it's the Dominator series, ditch it. Period. The Dominators don't actually give you any performance gains, they just cost more. Take a look at the XMS3 series or others from G.Skill (can't recommend them enough, but they're not every where), Mushkin, Patriot and really every where except OCZ (compatiblity issues).

HDD: The WD Caviar Black is an expensive drive. Grab a Seagate 7200.12 1 TB or Samsung Spinpoint F3 1 TB (whichever is cheaper, or the F3). They're just as fast, yet should be a lot cheaper.

Optical: BluRay is pointless for computers right now. Leave it out until the prices fall or a use emerges. Pick up the cheapest SATA DVD burner you can find.

GPU: While a good card, that price seems excessive. I know prices are higher over there, but that's almost double what it should be. Check out the HD 5850 or HD 5870, which you're likely to afford with the above changes. If you still can't afford them, you should be considering an AMD build. Check the prices on the X4 955 (or even X3 440) and a Gigabyte GA-790XTD-UD4. That'll free up a lot of budget to put towards the part that matters to gaming: the GPU.

HSF: The Corsair H50 isn't highly thought of. It's expensive, but not as good as a decent air cooler. Check out the Coolermaster Hyper 212 Plus or Scythe Mugen 2 (SCMG-2100). They'll be cheaper and just as good.

Damn,i accidently posted twice with only extra little more details.

Yes i know the prices over here in australia,are bloody expensive (excuse my expression) and the store owners are a rippoff.But that's nothing i can do about it.And they do put up the prices up to 50%-75% over price like you mentioned.Thats why i shop around and find a good shop to buy from,if i can,that'll be good.So far i only found one shop that are the cheapest in sydney.And that is www.skycomp.com.au for those who wants to buy stuff from them,there the cheapest so far but i have'nt checked it on the fair trading yet,but i will be tomorrow and if it is registered,thats even better.After that i will be going down in the city to check it if is there too.I thought of buying stuff from the amazon,i dont trust them.

Amazon would be fine. You're pretty safe buying from any larger retailer.

I also should clarify that of the Australian builds I've seen, the prices you've listed seem unreasonably high. The ones I've seen generally have a 20-30% markup over the exchange rate. The ones you've listed is a good 50%-75% above that. It just seems excessively expensive to me, enough that I'd find anywhere with at least a decent reputation to buy from instead.

From what Ive seen, most people are happy using MSY, they're prices are alright too:
http://msy.com.au/Parts/PARTS.pdf

Hello again.
I just found out today that the skycomp computer store in the city of australia,sydney,are registered with the fair trading and they are safe to buy parts from and they are not pushy either as i have spoke to them.The techbuy company and mwave company are not registered so there for dont deal with them.
I made few little change in the list for our i5 quad core gaming machine.The skycomp do have the aerocool syclone black/red gaming case.I asked about the corsair h50 cooler,it requires a more 50w power as they said so i got the 550w power supply from corsair instead of 450w which he said that will be enough to run the system and the h50 is is'nt loud either when running it.So it should be cool,it is low noise and has high efficiency with 120mm radiator fan.So i'll recap the computer i5 quad core gaming system and will be bought from the skycomp.

01:Aerocool Syclone Black/Red Case=$145.00
02:Corsair VX-550W=$109.00
03:EVGA P55 FTW Motherboard=$306.00
04:Intel CPU Core i5 760=$274.00
05:Corsair 4GB 1600C7 Dominator=$191.00
06:Western Digital Caviar Black 1TB=$143.00
07:Samsung SH-B083L Blu-Ray Combo=$101.00
08:EVGA GTX460 1GB EE SC Edition=$314.00
09:Windows 7 Home Premium 64-Bit OEM=$127.00
10:Corsair Cooling Hydro Series H50=$126.00

The total cost is $1,836.00.

Aww,damn,i think i just found out that the samsung spinpoint f3 is better than the caviar black in performance and price.Is that true?

Yes, like Admiral said, for performance and price you can't beat the Samsung

Cool,which hard drive should i get,SAMSUNG HD502HJ or the SAMSUNG HD103SJ?

I chosed the HD502HJ hard drive,it's better in terms of performance and price.