HTMLEntities as NUMERIC for XML

After reading this: http://validator.w3.org/feed/docs/error/UndefinedNamedEntity.html (all praise W3.org!) I am searching for a PHP library function that will convert all my &abc; into { I have a zillion of these things from converting stupid MS Word characters into something that will, like, you know, actually WORK on the Internet, and do not really want to re-invent the wheel here. Somebody has to have written this function... I'm kind of surprised it's not http://php.net/xmlentities or somesuch...