Mike,

Get your self one of the very latest credit card processing terminals like the TT41 / PDQ - they are "virtually" 100% secure and make it soooo easy for peeps to spend loads of money with you.........And if you dont like the fact that the terminal is silent (non interactive), you can allways do what I do and shout a "kurchuuuuung" noise when "payment authorised" is displayed on the terminal