Memory Tuning

I am looking for information on tuning memory usage for Postgres on Linux
(2.2 kernel). In particular I have a lot of memory relative to the size
of my database and am looking to reduce latency in queries.

Searching goegle turned up a few other cases of people asking about memory
tuning, but I didn't see any answers.

I have tried increasing the memory allowed for in memory sorts and the
estimate of available buffer caching. I haven't tried raising the buffer
space per connection as the documenation didn't seem to indicate
that that would help. This seems to have helped a little, but it is
hard to tell since the current delay is about 1 second and the queries
seem to happen faster when they are repeated after a short amount of
time.

For some idea of the specific problem, I am setting up a replacement
web server for my hobby server. The new box has a 1GHz Tbird with 500MB
of memory and a 20G 7200rpm IDE disk. The database is effectively static,
with rows for 300 games, 4000 people and 11000 people/game ratings and
a couple of other miscelaneous tables with a handful of rows each.

I am mostly interested in reducing the latency of requests while maintaining
the flexibility of using the database. Eventually there will be online data
entry so I don't want to switch to writing static files for the most of the
different possible reports.