pgsql 7.3.3 and odbc on linux ?

I installed postgresql 7.3.3 a few weeks ago, created a few toy tables
and now I'm trying to setup an odbc driver in order to connect
postgres to OpenOffice.  I've installed unixodbc and set up the `data
sources' in OO and it seems to work (eg. I can view my tables and
insert new values).

My /etc/odbcinst.ini file is:

[PostgreSQL]
Description    = PostgreSQL driver for Linux & Win32
Driver        = /usr/lib/libodbcpsql.so
Setup        = /usr/lib/libodbcpsqlS.so
FileUsage    = 1
Threading       = 2

What I do not understand is what is that psqlodbc package from gborg
and whether I need it.  Isn't the driver from unixodbc enough?

I browsed the docs and search the web for 3 hours but did not manage
to find an explanation.

thanks in advance,
panagiotis.