Data Entry Software with Database Integration

We are a marketing business that processes the sweepstakes for a large brewing company. In the past we've used simple spreadsheets to collect and manage the winners names, addresses and a few other pieces of information needed to verify them as a winner and then send out their prize. I would like to write a simple interface to excel that allows our sweepstakes coordinators to enter the winner's information into a standard template rather than a cell of a worksheet. And have that template linked to the worksheet behind it. Ideally I'd like to have the data verified through some sort of link to an address verification service to be sure the address as entered is validated against the USPS database of addresses. Would want this to work on a mac or windows as our coordinators use one or the other for data entry.