Очень достойный выбор!!!.
Я около десяти лет выбирал между Oracle и Interbase (FB) и пр.

PostgreSQL - достойный выбор как для веба (java,php,perl), так и для других (CBuilder,Delphi). Для Delphi есть VCL от www.microolap.com
Под FreeBSD говорят тоже нормально работает.
Я пользуюсь под SuSE или Redhat.
Есть также от Pervasive, оччччень стабильная версия.

http://www.pervasivepostgres.com/


Why Postgres?
Pervasive Postgres is a distribution of PostgreSQL, the worlds most advanced open source database. PostgreSQL has all of the features of a commercial quality relational database management system. It is SQL compliant, supports advanced features like views, stored procedures, and triggers, and scales to large numbers of users, tables, and rows. It is secure against unauthorized access through its sophisticated security system and resilient to system failures through its advanced logging capabilities. Its technology is production ready today.

Apart from technology, PostgreSQL is licensed under the business friendly BSD license. That makes it free for all uses, including use in commercial settings and embedding within closed source applications. Unlike software available under the GPL license, you can be sure your use is acceptable.