Now since you said you already ave the case and other componets you can easily deduct what you dont need, I would suggest making sure that your RAM can fit the MoBo and is not gonna dmg your new CPU depending on the voltage.
Also you can disregard the SSD if you dont really want one or your too unsure to get one and upgrade your GPU as much as you want
At this point, i would wait until LGA 2011 processors come out, then get an i5 or i7. As far as graphics, with a 400 budget (cause of mobo and processor) i would get either a Radeon HD 6950 if your going a little cheaper, or a GTX 580. As far as RAM, grab some 1600 DDR3 RAM, 8 gigs should be fine, and can be upgraded to 16 later if needed.
Just what i would do
so by performance standards do you think gtx 580 is worth the extra 200 or do you think ati puts out good quality 6950s build quality* and i was told to wait twice so i prolly will get the rest and wait for it
That GPU is probably the best 580 that Newegg has in stock right now. I would have preferred the MSI Lightning Xtreme edition for another $75 but this one is slightly faster and it gets you closer to your price point.
On your question 580 vs 6950, yes the performance is worth it, the 580 is significantly better.