Thanks, but the problem persists.
I type "su root", the computer replies with "Password:" I enter the password (no question that it is the one I installed OS X with, and it is the same one that I login with) the computer replies "Sorry"
P.S. I'd tried the sudo thing, but it didn't appear to work, but when I executed the sudo chown... command listed in your response, it did, and I could then modify the httpd.conf file. Hey, now I own it. I'm at a loss as to why I can't SU then just chown ... (perhaps also of interest, I can login with my OS X short user name, but If I try to login as root (from a shell), after the password prompt, it says "root login refused on this terminal." I'm not really a UNIX person so is there something wrong or just something I don't understand?
Thanks again, and the Series is really as thoroughly excellent as O'Reilly's books have been. Kudos!