I have a bank account and a debit card already. <rmah> from #startups mentioned that perhaps all I need is to just that debit card. Now that I think about it, he might be right! The question now is: Do we really need a credit card at all?
A credit card is a revolving line of credit, and it's useful if you need more control over when you pay your bills(e.g. paying the hosting bill on the third week of the month instead of the first). Note that I'm not advocating that you carry a balance from month to month - only that you have more control over cash flow if bills are getting paid on your schedule.