Cannot run pgAgent after install

Hi,
I'm running postgreSQL 8.1 (with pgAdmin III included) on a Windows 2003
Small Business server. I would like to setup postgreSQL so that it would do
some automated tasks in the database I'm using, so I decided to install
pgAgent. I have followed the instructions on
http://www.pgadmin.org/docs/1.4/pgagent-install.html but when I type in net
start pgAgent, it's saying the service is invalid. I've checked the postgres
database as pgAgent is installed there and the schema for pgAgent has been
created with the tables, triggers, procedures so I don't know where I've
gone wrong.

Any advise?

Cheers,
Ben