700-900 build first timer need advice

If you have the cash sawp the amd processor for a 2500k. and the gpu will be fine at the res.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
You should swap the HDD to a Samsung Spinpoint F3, its cheaper, higher capacity and its faster

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
I would also change the CPU to a AMD Phenom II 955 to save money

And if you don't have any plan on using a higher resolution than 1920x1080, then you could lower the GPU to the 1gb version of the 6950

Do you plan to to SLI or Crossfire those 6950s?

+1 on the phenom 955

not any time soon. on the crossfire or sli.

I would get this PSU. It's more than enough for a single 6950.

A Corsair 500w
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

There are cheaper options for modular PSUs if that is what you are looking for, both in the 650W range and the 550W range if you decide you don't need the higher wattage:

650W:http://www.newegg.com/Product/Product.aspx?Item=N82E168...
550W:http://www.newegg.com/Product/Product.aspx?Item=N82E168...

If you don't care about modularity, the Corsair builder series is a decent choice as mentioned above, or the Antec NEO series
620W:http://www.newegg.com/Product/Product.aspx?Item=N82E168...
520W:http://www.newegg.com/Product/Product.aspx?Item=N82E168...

just a note, the NEO series doesn't come with a power cable, but you can get one easily from Monoprice for $2-3 plus $1-2 for shipping
http://www.monoprice.com/products/subdepartment.asp?c_i...

actually im gonna grab a hd 6870 instead because of my tight budget.
would 500w b enough?

Yeah 500w would be more than enouguh.