Tweaking on an OpenBSD Machine

I'm looking for help from someone that has run Postgres 7.1.1 on a highend
OpenBSD machine.  We have LOTS of RAM (1.5GB) and we want to get Postgres to
use as MUCH as possible to speed things up.  What kernel tweaks have you
applied?  What login.conf changes have you made?  What have you done to the
postgresql startup to make it use this RAM?

Also, in addition to what changes that you've made, what are the defaults,
what does it mean, etc?  I need to get the system speedy (then I can use
EXPLAIN for further query tweaks) quickly, and I need to know what changes I
should make.

Alex