transaction logging

I'm interested in enabling transaction logging, so that I can audit
those logs on a system having issues.

Is there already such a log in postgres 7.4? If not, is there such a
feature and how do I enable it?

I looked in the docs and saw many logging options but nothing for
transactions.

Thanks,
Mike
--
Michael P. Soulier <michael_soulier@mitel.com>, 613-592-2122 x2522
"Any intelligent fool can make things bigger and more complex... It
takes a touch of genius - and a lot of courage to move in the opposite
direction." --Albert Einstein