I would recommend getting way more than 8 gigs of ram. At the cost, you might as well go with 32. You will be thankful for it as soon as you toss some displacement in the scene. Seeing “unloading geometry” will always ruin your day.
If you are really serious about going the 3D route, I would really stay away from the laptop. We have the top end dell and it will throttle itself after a bit due to the heat issues. Also, dont expect more than 2 hours of light duty CAD work on a machine with top end specs. I think that the desktop example given is a great one, and leaves you with 1k to get yourself a decent laptop to stay mobile. You can model/prep your scene on almost any decent laptop. Almost all the top rendering programs will allow you to distribute the rendering to the desktop to take advantage of the power it can supply. Also, you can upgrade the CPU on that machine if you ever want to later. And trust me, you will.
I wish I had more ram/processors in mine most days:
