What to buy for my computer??

[Cole Marcus]

Hey all im new to building computer and ect, i'm looking to get a Processor, motherboard, Graphic card, and maybe some Ram cards like 8G. Im looking to play World of Warcraft with this, so being able to play in ultra settings would be nice. I'm looking to spend $400. If i could spend less that would be nice. I would like to stick to Intel hardware.

[Transfusion]

You are looking to build a mid-end PC...

Intel i3-2120 ($127.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115077 
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i3-2120+%40+3.30GHz 
Top in terms of price/performance ratio.

Radeon HD 6850 ($139.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161384 
http://videocardbenchmark.net/gpu.php?gpu=Radeon+HD+6850 
Also top in terms of price/performance ratio.

Corsair Builder Series 600W 80 PLUS Power Supply ($69.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139028

Foxconn H61MX LGA 1155 Intel H61 Micro ATX motherboard ($54.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16813186213 

G.SKILL Value Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 ($36.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231422 

I do realize we are going out of budget here-total cost: $429.95.
I wouldn't want to step lower than the highest i3 for a gaming PC, and the Radeon HD 6850 does provide some measure of future-proofing. With that budget you'd be forced to get a Micro-ATX motherboard and budget RAM, though. Also: http://lifehacker.com/5415355/do-you-really-need-more-than-4gb-of-ram

As for the hard drive, you can just use the hard drive of the computer you are using now regardless of whether it is a laptop or desktop, and as for the chassis, if you are using a desktop, by all means, reuse the chassis, if not, any old ATX one will do. If you have a desktop DVD drive, also reuse that, if you have a laptop,  get this:
StarTech SLMSOPTB USB to Slimline CD/DVD Optical Drive Black External Enclosure ($21.99)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817707222&Tpk=slimline%20dvd%20enclosure

Oh Darn we still have to factor in the cost of Windows...

Now we are wayyyy out of budget, aren't we?
Tell us the specs of your current PC , perhaps an upgrade will suffice.