How might I determine this?
netstat -a -n this will list you all current listened ports you could also try and telnet localhost 5432 to see if something is listening.
Would this make a difference when the system is rebooted vs manually restarting the server?
when another program is occupying the port, it would probabyl not make much difference, except if the pgsql service is started before the other tool.
maybe pgsql is already running? ;-) cheers,thomas