A better way to convert would be to use iconv, see http://www.php.net/iconv -- example:
<?php
$myUnicodeString = "Åäö";
echo iconv("UTF-8", "ISO-8859-1", $myUnicodeString);
?>
Above would echo out the given variable in ISO-8859-1 encoding, you may replace it with whatever you prefer.
Another solution to the issue of misdisplayed glyphs is to simply send the document as UTF-8, and of course send UTF-8 data:
<?php
# Replace text/html with whatever MIME-type you prefer.
header("Content-Type: text/html; charset=utf-8");
?>