Well, with quite a good deal of work, I think I was able to make the GTX 670 work within your budget (I was about to give up and go to the GTX 570, but stuck with it and am pretty happy with the build).
It comes down to around $1150-$1200 after instant discounts, but has a an Ivy Bridge CPU and modular PSU (which costs you about $20 extra, but IMO is worth it). I'm not sure how you feel about rebates - everyone's had a different experience, so keep in mind that it's not "guaranteed" money (I've always received mine, but plenty of people haven't) and it's definitely not a fast return... with that said, this setup has about $70 in rebates, which brings it closer to your range.
I think that cuts it down to your $1500 limitation... but I'll find that out after I type out the list
Motherboard: ASUS P8Z77-V -
www.newegg.com/Product/Product.aspx?Item=N82E16813131837 - $145 ($125 after MIR).
CPU: Intel Core i5-3570k (Ivy Bridge); use code EMCNDHB34 at checkout for $15 off -
www.newegg.com/Product/Product.aspx?Item=N82E16819116504 - $230 - $15 = $215
Memory: Corsair Vengeance 8GB 1600MHz memory -
www.newegg.com/Product/Product.aspx?Item=N82E16820145345 - $50
PSU: OCZ ModXStream Pro 700W Modular PSU -
www.newegg.com/Product/Product.aspx?Item=N82E16817341018 - use EMCNDHA22 at checkout - $90 - 15% = $77 ($47 after MIR)
Case: Zalman Z11 Plus -
us.ncix.com/products/?sku=69199&vpn=...ECH&promoid=1223 - use 69199-1223 at checkout - $70 ($60 after MIR).
HDD: WD 1TB HDD -
us.ncix.com/products/?sku=58881&vpn=...0WD&promoid=1223 - use 58881-1223 at checkout - $88.
SSD: 120GB FORCE -
www.newegg.com/Product/Product.aspx?Item=N82E16820233206 - $115.
Optical: I'm hoping you have one of these from an old machine that you could re-use, but if not -
www.newegg.com/Product/Product.aspx?Item=N82E16827106289 - $18
GPU: GTX 670 -
www.newegg.com/Product/Product.aspx?Item=N82E16814130787 - $420 ($10 after MIR).
Comes out to ~$1198 before rebates. Somewhere around $1150 after. Add the $73 mouse, monitor + keyboard at $293, and Win7 64bit for $100, that puts you at $1614.
So how do we come down a little more? Well... I think I can figure that out, actually, but give me until tomorrow - I need to sleep at some point tonight
Here's what I'm thinking to cut prices:
1. See if you can locate an optical drive that's not in use in an older PC. Make sure the optical drive is compatible with SATA.
2. We can cut the CPU to an i5-2500k, which won't be a massive difference in gaming, but will save $30 if we use MicroCenter.
3. If you have the time to do it, check the above products against MicroCenter's pricing (sometimes they only offer the excellent prices in-store, so check for that - unless you're near one).
4. We could drop the GPU a bit, though I want to try and keep it.
The case, though, is the best deal I've found through this whole search. It's the weekly deal, so we might have another few days to decide, but if you aren't opposed to the exterior looks of that case, it's tough to beat for $70. That said, if you like the R5 (I have a review sample next to me this second, actually, and I quite like it), stick with it.
I'll re-convene when I awaken