>>>Isn't there a setting somewhere that I can show slashed zeros, so my clients won't confuse them with the letter "O"?
>>
>>The only way I know how to do it is to select a font that uses a slashed 0
>Know of any?

Off the top of my head, no, but I know we use them. I'm fairly certain that one of the OCR fonts uses a slashed 0, so you might look at OCRA and OCRB.