OK, IT guy here. Sorry for the long post but I hope this advice helps.
I've read everything up to now and it all makes sense and I agree. So far, the info, comments, opinions, corrections, etc all add up and make sense. No need to repeat it all again.
My primary advice is that you take your time. Build it, install Win7Pro x64 OS (great OS choice at this time) to a decent SSD like maybe an Intel 520 series or Samsung 840 Pro series and then systematically install all the updates and find the most up to date drivers. Get a solid motherboard from ASUS, Intel or several other reputable companies. Don't buy cheapo motherboard+CPU deals. Buying the motherboard is usually my hardest decision. Make sure the BIOS is fully updated. Make sure the USB3 firmware is fully updated. Put your catalog and/or photoshop cache files on the SSD. Store the actual image files on a secondary large RAID protected volume. Don't buy cheapo RAM. Stay with Crucial, Micron, Kingston, PNY, G.Skill, Patriot, etc. The reputable motherboard manufacturers usually have lists of RAM they certify to work that they tested.
Once all that is done, do an image backup and start benchmark/stress testing the system with file transfers, benchmark utilities, etc. Make sure you are getting the performance of the CPU, RAM, Drives, Motherboard, Video, etc that you paid for.
Oh, and get a high quality power supply. Get a large tower case. (Antec 300 is a good choice.) You'll be adding drives, believe me. Get something that is at least 750W. Real watts, not cheapo watts. Something like a good Corsair unit. If you paid less than $100 for the power supply, it probably isn't good enough. Newegg has great informative IT geek reviews and will likely help you get a good unit for your needs.
Put this system and the display on a UPS with AVR. My Costco regularly carries the CyberPower 1350AVR for around $100. It's a great unit and it's on Newegg for around $145. Just get one with AVR. Direct power from the wall (the grid) isn't nice to your sensitive electronics. I have a good UPS on everything in my home that is electronic and worth more than $100. You know, like that $3500 plasma tv! It's not a guarantee against calamity but it's better than nothing.
Don't go overboard on the video card for a photo pc. Most of the performance benefit will be gained from the SSD, CPU, RAM, USB3, then video, etc. Spend the video money on a nice high end IPS display and calibration tool. Maybe get dual displays but one large high end IPS panel is better than two cheapo LCD panels. Put in plenty of storage in RAID 1 configurations for working data storage and individual internal and external drives for backups.
The hard part isn't just the hardware, it's setting up the software, getting an effective sync/backup system in place and then keeping up with it. You can't have too much backup. Consider an offsite solution as well, online or physically carrying external drives to another location or both. Online is good for data but not for recovering the system so you need a local image backup of at least the system drive.
Finally, don't use this nice fast photo pc to do everything. If you install a bunch of stuff like QuickBooks, Office, HP Printer software, huge antivirus security packages, etc, you will kill the performance. Just use it for photography. If you don't use it to surf porn, play online games or do your online banking, don't install antivirus or just install the perfectly fine Microsoft Antivirus. Seriously, you'll thank me later.