A few months ago, I invited a less-technical friend over, to have him build a new PC for his GF. It went pretty smoothly, but he was getting tired of doing it after an hour or so, so when it was fully assembled, he had me install the OS for him. (Win7 updates would have taken another few hours, although that goes faster now that there are "fixes" to the update issues, with the right patches installed first.)
Only problem is, he doesn't really remember how anymore, when I asked him recently. It seems he prefers to be clueless, about the art of PC building.
Edit: I suppose, the moral of this story is, it goes a lot smoother building your first PC, if you have someone assisting or directing, that has experience building them.