ODBC fails connection

I've got MSAccess2000 under WindowsXP and Postgresql7.2 under Linux.
And I would like to use Access as a client.
I've dowloaded the ODBC driver7.2 and when I try to make a source of data I
have three optional drivers:
PostgreSQL 7.02.00.03
PostgreSQL+(Beta) 7.02.00.03
PostgreSQL+Unicode (Beta) 7.02.00.03
I've chosen the first one and I have to fill in several fields in a dialog
window. Here are the fields and my questions:

Data Source: PostgreSQL -> Right?
Database: Name_of_my_POstgreSQL_database -> Right?
Server: IP address of my Linux machine -> Right?
Port: Don't know?
User Name: Does this user need to be created in the database and
also as a Linux machine users?
Password: The same question
----------------------------------
I've created a PostgreSQL user but when I try to connect from ACCESS I open
ODBCdatabases; choose Equipment data sources; choose the PostgreSQL (Sistem)
Data source; Accept; and apears a dialog; where I fill in a user name and a
password; butget the following message:

ODBC: fallo la llamada -> (the call failed)
Could not connect to the server;
Could not connect to remote socket (#101)
-----------
Please. Any help?

Regards

--
A. Javier García
Water and Soil Conservation Department
CEBAS-CSIC
Apartado 4195
30080 Murcia
Spain

Tel.: +34 968 39 63 90
Fax: +34 968 39 62 13