I finally found a post on this in the Joomla forums, which said that PHP 5.3 is not compatible with the latest version of Joomla, 1.5.14, and that you have go back to an earlier version, 5.2.x. Once I did that, it is all working fine now. See the following thread in the Joomla.org forum:
Hopefully this information may help another Joomla/WAMP novice like myself and save them a few days
Forum:
WampServer English