To invert a character class, add '^' to the beginning of it: Also, you want to use the + (one or more) quantifier instead of * (zero or more). Otherwise, you end up inserting an underscore at every other position.
If you use a +, you will replace each sequence of special characters with a single underscore. If you omit the + (and don't use * either), you will replace each individual special character with an underscore. Depends which result you want. [ March 20, 2007: Message edited by: Peter Chase ]
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.