I came here to tear this apart, but am pleasantly surprised to find that this article is very well done and practical. About the only two nit-picky things I would point out is; that to do the actual editing you can do just fine (at least for 1080p editing) on the entry level with an i3 processor and onboard Intel graphics. Yes, you are not going to get much in-software acceleration for effects, and your export may take a little time, but it is more than enough power to import your clips, set your cuts and transitions, and export overnight effectively on the low end for those starting out. Certainly you would want to move up to an i5 with whatever GPU acceleration is supported by your software of choice ASAP (especially as your income comes to depend on it and rendering time begins to cap your income), but to say that it is required for an 'entry level' system is really underestimating what a modern i3 can do.
The other little point is that I would never be able to suggest a single HDD even on the entry level. Your storage drive should at least have a RAID1, or you should have a nice fat USB3 external HDD or NAS of some sort to off-load video. Drives fail, it is just a fact of life. But drives are also cheap, and just about every board under the sun comes with a basic RAID controller. I would much rather spend $75 on a 2nd 2TB drive for the worry-free uptime that it brings to the table than $150 on a GPU that is going to have minimal impact on the editing process, and merely accelerate exports which are likely going to be done at the end of the day and are much less time sensitive (at least when starting out). Faster exports are a nice perk, but catastrophic drive failure is catastrophic.
Still, great article, and full of great information that is sorely lacking in the forums.