Computer Upgrade. Want smoooth proformance

[Ogloo]

Ok, so right now I have a crappy computer that has managed to run 4 wows in 1700 bracket last season.. I am needed more power If I play Wrath.. (back from a break,, but i have a 80 already) i have my shaman group at 72,but i need more power..
As for upgrades, I plan on upgrading my CPU, RAM, videocard, Motherboard, what else do I need to fully upgrade my system? i know power, (please tell me what power I need for these upgrade specificatoins.

CPU- Intel Core i7 920 2.66GHz 8M L3 Cache 4.8GT/sec QPI Hyper-Threading Turbo Boost LGA1366 Processor
RAM- Corsair TR3X6G1333C9 XMS3 6 GB 3 x 2 GB PC3-10666 1333MHz 240-Pin DDR3 Core i7 Memory Kit
Videocard- I am not sure what is really needed for a videocard, other than making it look nice, does a videocard actually make the movement smoother? or is there just more detail? I want something that looks nice and will run smoothly.. not really sure.. maybe a raedon?
Motherboard- Intel DX58SO Extreme Series X58 ATX Tri-Channel DDR3 16GB SLI or CrossFireX LGA1366 Overclocking Utility Desktop Board
Cooling/power- how in the would I know how much power and cooling i need for these 4 upgrades? also is there anything else?

Should I might as well buy a new computer? thanks

This is my system specifications

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[Multibocks]

OC the proc to 3.6ish Ghz and then maybe up the ram to 12GB. The video card I would say Nvidia 285 or a Radeon 4870x2 or whatever is cool now. No need to use 2 cards with WoW. ( yes I realize the irony of recommending a 4870x2 )

[Enndo]

Right now im using a i7 920 with 12gb corsair 1600, and a gtx 285 superclocked and it runs very smoothly, you should look into a 750w power supply or better to push it. I went a little crazy with the video card, you really could go with a gtx 275 which is like $150 cheaper and will only be a few fps slower. As far as ram I wouldnt bother with 6gb as its so cheap now lol. Go straight for 12 than you dont gotta worry about upgrading later. As far as brands i like going with stuff that has great reviews, won awards etc etc, everything in my case is evga, and corsair, with the exception of the intel chip lol, o and the coolermaster v8 ive got chilling my chip.

Intel 920
coolermaster v8
evga board (lifetime warranty!)
corsair ram
corsair 850 power supply
evga gtx 285 sc