After reading the hint entitled Disable Command-Q for quitting applications, I becamee inspired and started experimenting. Here is what I ended up entering in my terminal:
defaults write NSGlobalDomain NSUserKeyEquivalents
'{"Quit Safari" = "@Q"; "Preferences..." = "@;";}'
[Enter that on one line, with a space before the single quote that starts the second line above.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030508130108314