the NZXT gamma case is my FAVORITE bang for the buck case, it has awesome cable managment, great airflow, dual top exhuast ports black interrior, bottom mounted powersupply, it can house 6 fans. its just an awesome case that screams bang for you buck.
the sabertooth motherboard from asus offers amazing features for the money, another piece of hard ware that gets you the most bang for your buck. it has dual 16x pciexpress slots, that will break down to 8x 8x in crossfire/sli. its just an awesome board for the price
the i5 platform is an amazing platform, especially if you arent doing mulitthreaded tasks like video editing that tak advantage of the hyperthreading that the i7 platform has. the only difference between an i5 and an i7 is hyperthreading. and if you arent going to be able to take advantage of that, why pay the extra price? the i5 beats AMDs fastest 6 core processor in some applications.
the memory i chose isnt really all that great, but for what you need its perfect. you can literally spend $900 on Ram, but thats not necessary. for what you are going to be doing, the ram i chose is going to do just what you need.
the 6870 is an awesome card and there really isnt any software ( games ) that can fully take advantage of its hardware. you will see this card shine more and more in the comming months as newer games can take advantage of what it has to offer. at the moment its faster than the 5850 but not quite as fast as the 5870, but its cheaper than both. When software can take advantage of its hardware, the 6870 will pull ahead of the 5870
i the powersupply is an awesome powersupply, it does what 90% of builders need and does an awesome job at it. its a corsair powersupply so it has a 5 year warrenty. i never build a computer with anything but a corsair powersupply.
hdd is a caviar black 7200 rpm drive, really standard these days, nothing special there
the CPU cooler is THE BEST bang for your buck cooler on the market. with 2 fans on this thing it gets temps way outside its price range.
thats about it i suppose
good luck mate, dont be afraid to ask questions, no matter how silly it may seem to you. thats why we are here, to help you.