re: jason at omegavortex dot com below, another way to deal with whitespace issues is:

        function charData($parser,$data)
        {
            $char_data = trim($data);

            if($char_data)
                $char_data = preg_replace('/  */',' ',$data);

            $this->cdata .= $char_data;
        }

This means that:

    <p>here is my text <a href="something">my text</a> 
    and here is some more after some spaces at the
    beginning of the line</p>

comes out properly. You could do further replacements if you want to deal with tabs in your files. i only ever use spaces. if you only use trim() then you would lose the space before the <a> tag above, but trim() is a good way to check for completely empty char data, then just replace more than one space with a single space. this will preserve a single space at the beginning and end of the cdata.