This is John's response to this question:
5. I know that many folks can only pay via paypal or credit card. I'm sorry but at this time we can only accept checks. It goes beyond the fee involved for processing. It has to do with the accounting as well. Since this is for a charity the amounts collected and paid to the charity must be clearly documented. With the checks it is simple - the money coming in is the money that goes out. If we involve a service that imposes a fee, or a seperate account (like paypal) then the accounting becomes a nightmare.
Actually John's whole thread provided some really good info:
http://www.disboards.com/showpost.php?p=29966612&postcount=84