WorldPay integration into existing PHP site

I have developed a LAMP website that features a 7 screen checkout process that helps the customer to select and configure a tour. The tour information includes all of the things that are needed to support the tour (food, catering, drinks). There are about 50 things that they can choose and a detailed invoice is already generated by the system. ALL I NEED is for someone to help me connect to a CREDIT CARD GATEWAY to bill the total amount. I have never done this before. My preferred vendor for this is WorldPay. I am looking for someone who has *already* integrated WorldPay with a LAMP application. If you have *already* activated a WorldPay account please say so in your bid as this is our first time and we could use your help if that vendor is picky/tricky in terms of setup. I am looking for someone who can accomplish this task within a two (2) or three (3) business day period once our WorldPay account has been activated. Thank you **BEFORE YOU BID** please review the Clarification Board