Reading the porting guide will help a lot, especially if you are just programming pages and things like that.
PostgreSQL is much simpler to install and administer than Oracle. Read the PG Install Guide (which is missing a statement on the installation part that I need to correct before 3.2.4 is released) because it has tips on maintaning, backing up and the use of "VACUUM ANALYZE" which is essential to performance.
I plan on expanding the porting guide with information on how to port PL/SQL Code to PL/PgSQL and PL/Tcl sometime next month or maybe end of this month.
