OK, IT guy here. Sorry for the long post but I hope this advice helps.
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.
Thanks RustyTheGeek, that's a very fine, generous post. Home PC builders should bookmark this one.
Your final comment is an area that is too often overlooked. My photo PC's do just that...all that's installed are the required Adobe CC components, PhotoMechanic, Firefox, Microsoft Security Essentials and a handful of required utilities.
All the Office, MYOB, iTunes and basically unnecessary entertaining stuff is on a separate modestly powered machine, in this case an entry-level Mac Mini running OSX Mavericks and Windows 7 installed via VM Ware.
Thanks for the kind words pwp. Yes, these days hardware is cheap. People sometimes don't realize the benefits of having more than one physical system. Esp if they have kids!! Another option is running a separate VM system. I've been doing this for over 20 years and it still amazes me how poorly written most software is. It's actually much worse than it was even 10 years ago. Lazy or overworked programmers and unrealistic deadlines and/or not much talent. It's sad but this is just the poor state of affairs most software companies are in these days. Look at how long it has taken to get a version of Windows out in the past 10 years and then look what we ended up with! And Adobe regularly releases buggy code.
Most of the time it pays to keep things as simple as possible.