I\'m using delphi for years, but never for database stuff, but recently started researching and testing.
I must say, i\'m impressed, most of things happens automatically
@arthurprs, for you scenario
(2 layers) 5 user computers, 1 > database server.
alt text http://www.techsolusa.com/images/firebird-logo-64.gif The Firebird RDBMS is a very good option , because is very stable, fast, runs on Linux, Windows, and a variety of Unix platforms and meet with you requirements.
alt text http://d.yimg.com/kq/groups/12858579/homepage/name/homepage.jpg Respect to the components for connection i go for ZEOS.
I have used this combination in many small and medium projects, with excellent results.