problems with postgresql speed

Hi.

I've serious problems with the speed of my database.
If I execute any query like this;

SELECT d.gallery_id, e.subevent_id, d.result_type_id,
d.result_type_name, e.language_id FROM ((SELECT b.gallery_id,
b.element_id AS result_type_id, c.name AS result_type_name FROM
gallery_element b, result_type c WHERE ((c.id = b.element_id) AND
(b.element_type_id = 10))) d JOIN (SELECT b.gallery_id, b.element_id AS
subevent_id, c.language_id FROM gallery_element b, view_subevent_info c
WHERE ((c.subevent_id = b.element_id) AND (b.element_type_id = 9))) e ON
((d.gallery_id = e.gallery_id)));

The result take a minute, or more, to show the results.
The postgresql.conf I used is attached to this e-mail.
The table "gallery_element" have 8644 rows, and it have got 25932
registers.
The machine has 512 Mb RAM and 1.4 PIV processor.

Thank you very much.

--
Manuel Trujillo         manueltrujillo@dorna.es
Technical Engineer      http://www.motograndprix.com
Dorna Sports S.L.       +34 93 4702864