It is worth noting that you can buy pc's pre build without all the extras. For example: click here is why I am wondering whether we should build or buy prebuilt...
If build thats no issue as ive built pcs in the past. I just dont know how much better the build will actually be building it ourselves vs buying something like the link above at cclonline.com
I would recommend giving Chillblast, Scan or CCL Computers a call and configuring a prebuilt with an 8th gen Intel i5 CPU, 16GB of RAM and a 1TB HDD.
I did a check on CCL and a prebuilt like this can be had with 3 year on-site warranty for £480 without Windows 10. Do not go lower than 8GB of RAM for an office build especially if running graphics software and multitasking.
Why prebuilt? Well if you build it yourself and a component fails you will have to diagnose which component is at fault, pull that component, contact the manufacturer and arrange an RMA, then send that component off and wait.
With on-site repair a technician comes to you and has you back up and running within 1 business day. Ideal if you have a small business without an IT technician or don't want to buy spare parts while a component goes off for warranty repairs.
Dell and HP also offer systems with On-Site repair for businesses (that's one of their premium support options).
Kevin Alders - If CCL is all you've picked up from my post then you haven't read it fully. Especially since 4 other manufacturers were put forward.
Back to the subject at hand:
I've checked the Adobe website and 4GB is the minimum requirement recommended for the current versions of Photoshop and InDesign. Adobe recommends 8GB so again don't go below 8GB.
The reason I'm also recommending newer hardware than those in the poster's link is that Windows 10 is an OS as a service.
So far only Atom CPUs have fallen to not being suppored by the latest updates of Windows 10. Going newer means that if Intel or AMD drop support for any hardware in future the newer models are more likely to continue getting updates for a while longer.