In your earlier discussions with Andy he talked about the open firmware password being set.
This is set in a chip inside the computer and not on the hard disc. (changing the HD doesn't change this password)
This is available as extra security to stop the mac being booted from another disk...
Above these three tabs in the preferences window, there should be a row of icons (Do you see them? - I lost them once under 1.3) One of these is the signatures preference.
I tried out the Oracle9i Release 2 - Developer's Release available at;
http://www.oracle.com/technology/software/products/oracle9i/index.html
It worked under regular OSX - I had the developers tools installed but I can't remember if the install needed it.
There is more information about...
If you register (free) on the oracle developer site at http://technet.oracle.com you can download both 9i and 10g for OSX.
You can use these for development use.