[eluser]TheFuzzy0ne[/eluser]
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You can do that if you want, but you should also be sure to convert the remaining string to HTML entities.
Code:
$str = htmlentities(strip_tags($str));
If removing HTML suits your needs, then do that. On my forum I'm going to just convert the text to HTML entities when the text is inserted into the database, just in case someone wants to write HTML that isn't parsed.