postmaster tuning commands

Hi all...I'm trying to get the most optimal tuning parameters for my 
database.....

Currently I'm using the following command line optinos to postmaster.....

postmaster -B 128 -S -o -F -S 1024

None of the postgres processes last very long, but some of the queries 
can really chew
on resources and disks....

What are some of the parameters people are using or have found to be the 
optimal? I'm running
on bsdi 3.0...but am contemplating moving to one of the linux variants...

-=pierre