How to run multi-processor question

Howdy:

Running Postgres 7.1.3 on RedHat Linux 7.2 kernel 2.4.7
on an Intel box.

We are thinking about upgrading the box and adding a
second processor.  Provided that I can physically put
a second CPU in, how can I configure Postgres to
work with more than one proc, or better yet, submit jobs
to the least busiest proc.  What other things should I
be aware of?

Thanks!

-X