This article opens with "This article is primarily aimed at interested users ... but it still helps to be more expert"...and I completely subscribe to that view. It is a very well written and therefore very readable artcile for all of those interested in this subject.
Highly recommended.
"This article is written for Windows users who want to know what is happening during Windows startup. My goal is to make Windows startup more easily understood by the average user. So I have provided a lot of basic information for those of you who aren't familiar with Windows terminology. This article will be most useful to advanced users because it provides detailed startup sequences and examples. This could be helpful if you are trying to troubleshoot Windows startup problems so I have included some pointers for where to look for particular problems.
The article moves from background material to a simple overview which is expanded upon by looking at the various Windows processes with examples of their processing steps. Wherever possible I have confirmed the steps in a real example but I've still had to rely on other commentaries as I've only used the tools that would be used by a confident user. That's why there is no mention of advanced tools for programmers like kernel debuggers or the special debug version of Windows (a checked build)."
Full Article