Architecture and patterns for cash collection terminals

I have just been handed a huge project for an application that must run on a terminal that securely collects cash drops. It is a rewrite of an existing project, so requirements are pretty well defined, this is the product. Although my employer will supply me most application specific new requirements, I would like some general advice on architectural aspects and areas that I should pay attention to in order to ensure maximum quality fo开发者_高级运维r my rewrite. The application will run on XP Embedded.

Hopefully folk who have written such applications can maybe advise me on areas to focus on.

Unfortunately I have no experience with what you are going to implement, and I didn't take this book, but when I read your question I just remembered its title and idea that it can be useful pop up: "Real-Time Design Patterns: Robust Scalable Architecture for Real-Time Systems" (check also book advice from amazon customers under that book)
Here is google book link, so you can check its content

Btw, you will have client-server systems, maybe another integration needed, so there is another interesting book in that area which I read: Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions and alternative, similar catalog of SOA patterns http://www.soapatterns.org/ - just in case you will need integration and its security.