Where in the Pacific are you?
Once you know what you are going to buy, try a website by the name of pricespy, I know there is one in NZ:
http://www.pricespy.co.nz/ and another in AU:
http://www.pricespy.com.au/.
It lists every computer retailer in each country respectively and then lists their prices so you can quickly see who is selling each component the cheapest.
As for a gaming rig, well as already said, you are best getting a Xbox 360 if your only need for upgrading is for games. Otherwise you will be upgrading every year just to keep up with new requirements. With an Xbox 360 you are gauranteed that all games made for the 360 will run...
Having said that, if you are like me and like builiding computers, you will build a new one anyway...
Best way to start is to identify how much you want to spend and then build the best within your price range...
How much do you want to spend?
By the sounds of things you prefer Intel over AMD so you can also build a system around that CPU if you like.
Just be careful you do not create bottlenecks and waste your money. Remember your systems performance is only as good as its worst component.
In my opinion the most cruitial component is the motherboard, get one that supports quad core etc... You can always start with a cheaper dual core cpu and less ram, slower gpu if need be and upgrade later...
Also don't get enticed into a cheap PSU that claim a high Watt rating, look for brand as it can make a big different, anyway if you can let me know your budget I can be much more specific.
Good luck.