Is there some type of Daemon that can look at pgsql?

I'm trying to create a program that would look, at a specified interval of
every 15 seconds, at a database; if there is a new entry(which would be
specified as a field called IMSTAT), it would need to start a process of
copying a .tif file from a local drive and then create a dynamic HTML page
from this .tif. My end users would be passed an URL of this newly created
page.

After completing the dynamic page, then I would modify the db records to a
completed status and then the system would again check to see if any new
entries existed.

Is pgsql the way that you folks would do this or is there a better way/some
existing daemon that can monitor pgsql?

We currently run Apache 1.3.6
Postgres 6.4.2 (I know this needs to be upgraded)
on a Mandrake 5.2 box (essentially RH 6.0)

Thanks for any and all help,
Shawn