W7 personal config/looking seems safe to go the new user.
Just delete the user's files is not enough?? why?
You can just delete the user files if you wish - the problem is there are 10,000+ user files on that PC. Not all "user data", but user preferences, actions, most recent opened files, etc.
It is safer and easier to just "wipe and load" a fresh image on a PC you are going to give to a stranger.
This makes life easier for the buyer because a new install of Windows is the same for everyone. It makes life easier for the seller because 1) no inadvertant data left on the machine, and 2) no questions about "how does this work, you did this"

For a family member it may be OK, for a stranger it can cause a refunded PC sale
