I think you will find that iconv is included in the base php5 package but I'm not sure if it is enabled by default.
So if you don't have php5 setup already it would be a good idea to upgrade if you intend on running Joomla 1.5+ on your server.
See here for Joomla Minimum System Requirements:
http://help.joomla.org/content/view/1938/302/
Please post back with your results as others might find the information helpful.
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