Plug-in to manage customers

Hi there,

My client - a plumber - currently uses pen and paper to record all his customer details but I'd like to suggest that he comes into the 21st century.

Can you recommend either a, plugin that will allow us to manage approximately 500 customer details (name, address, ph, email, notes) or have you had any experience where a Wordpress plugin has successfully communicated with third-party CRM software?

I'd like something seamless and simple for him to use, tradesman tend to be quite slow on taking up any new online/computer responsibilities.