Heres a silly question, once he has all the componants together and turns it on, what then? Will it ask you to load the OS (xp vista ect) Will he have to load all the drivers for all the componants? Does it do these things automatic? Will the computer walk him thru what to upload and in what order? This is the single biggest hesitation i have in building one as i am far from computer literate. I know i could assemble it, but getting it to work once i turn it on is another thing
When the computer is first turned on, it will POST (like any other computer) and if there is no disk in the cd/dvd drive, it will "Invalid System Disk or Disk error". At this point you will put in your windows disk and reboot the system (power switch or ctrl+alt+del). Then you just follow the menus to install windows. Once windows is loaded then you can install the drivers. A disk will come with your motherboard which will have drivers for the motherboard itself, USB, sound (if integrated), network (if integrated), and video (if integrated). Sometimes windows will automatically load drivers for you and sometimes they are the correct ones, and other times they are 'generic' ones.. but it's a crapshoot. I like to install the proper drivers.
If I have network connectivity at this time then I will throw away the motherboard disk and download drivers directly from the website for the motherboard. The ones on the disk are usually out of date by the time you get it out of the box anyway. If I don't have internet, then I'll install only the drivers I need to get on the internet, and then download whatever I need... or ideally you'll want to use another computer to download whatever you need onto a flash drive, and then use that to install the new system.. *IF* you're that paranoid about viruses.
If you have any add-on cards (video cards, sound cards, etc.) again forget about the disk and download the drivers from their websites. Once all the proper drivers are loaded, then do your windows updates... you can wait for it to do them automatically, but I like to do it manually if I can on a new system. Once windows updates are all complete, unplug the internet, reboot the system again and then this would be the perfect time to make a hard drive image for backup purposes.
Once a backup image is made, then this is the time you'll want to install your anti-virus software, flash (if you want), java (if you want), aces high, firefox, and whatever else you use.