I have three personal cards: Mastercard, American Express, and Diner\'s Club. The Diner\'s Club is for use on company-reimbursed expenses only. I also have a Visa card with a $100,000 limit that is used for company purchasing only. I don\'t carry that one around with me. It stays locked in a drawer at my office.
I use the MC and Amex all the time to replace cash. I don\'t understand why so many people say they "get in trouble" with credit cards. Just pay your statement in full every month, and there\'s no problem. If you know you won\'t have the money to pay in full when the statement arrives, then don\'t buy it. I don\'t like to pay interest to credit card companies for the priviledge of spending my own money. I save it first, then spend it.

BTW, it\'s good to have a few credit cards to develop your credit rating. It\'s bad to have too many though.