Ever tried to su to root in terminal? here's what happens under OSX 10.3:
$ su
Password:
su: Sorry
... and here's a quick fix ... add the following to your ~/.bash_profile file (in your home directory) using your favourite text editor:
alias su="sudo bash"
Restart terminal, and away you go!
$ su
Password: [type your password, you must be an administrator]
02:03:06 | compy386:~ root#
Be careful what you do, the slightest typo could zero your hard drive!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040509200602480