Actually, Universe Builder is specifically for building universes based on OLAP cubes. For regular databases you use Designer.
However, be aware that unless you database is fairly simple, there can be challenges to building a universe. Basically, a universe is a "metadata layer" between the user and the database. It hides the complexity of the database from the user and allows users to chose fields based on plain English (or whatever spoken language you're using) labels. WebI then builds the SQL for the report based on the fields that have been selected.
When building a universe, you have to be aware of possible circular references because they will cause an error. There are several different ways of resolving circular references - Context, Aliasing, Derived Table - each of which can be appropriate in different situations.
Seeuni, if the universe will be used by you only, then you can set it up based on your tables and it may be a very quick setup for you. However, if regular users will ever be using it, there's a fair amount of planning that goes into making it user friendly. At that point I would highly recommend that you take the Universe Designer class that is available from Business Objects.
-Dell