You should probably go to the top level of this web site and start reading. OpenACS doesn't use Oracle. It's a full open source solution; as a matter of fact, I think one of the initial reasons to do OpenACS was to get away from Oracle.
I guess Don and others will tell you the differences about OpenACS and Classic ACS-Tcl and how OpenACS will move forward, but you can start off by forgetting about Oracle.
