Securepay and other online credit cad processors require you to have your own merchant account. This can be very costly. Fees quickly add up, and you need to submit credit and bank applications for a merchant account. You pay reporting fees on a per transaction basis as well as monthly administrative fees. Then, you need to deal with any fraud and credit card disputes, and pay fees for any chargebacks. If you take a charge from a guest that later disputes that charge, you don't get your money back for the transaction fees you've already paid.
An alternative solution, allowing bed and breakfasts to accept credit cards without a merchant account, has just been introduced by Instant World Booking. Here's the page that tells more about their service, called IWB Payments:
http://www.instantworldbooking.com/payments-systems.php