no, i don't think geocities supports php.
it sounds like you are on the right track. php runs great with IIS, so you can just use your local web server for now.
once you get it installed, restart IIS and make a script that looks like this:
PHP Code:
<?
phpinfo();
?>
save it as phpinfo.php in your web root directory and try to launch it from your browser:
http://localhost/phpinfo.php
hopefully you will see a big long page with all your php information on it.