memory allocation ; postgresql-8.0

      Hi,

I am reserving 2.1 GB of memory for postgres to use with SuSE linux 9.0
(SLES) in sysctl.conf.
I have configured postgres to use 1.9 GB of memory so it won't go over
the 2.1 cap (postgresql.conf).
I have a total of 4GB of memory.  Somewhere I read to keep half of the
memory for other things.  This server is dedicated to postgresql.  Does
anyone agree with just using 2GB?  Does anyone know where I might have
read that?

Thanks,
Dj