I was pleased to write a white paper with Randy Johnston a couple of years ago for CPA.com called “The Journey from Premise to Hosted to Cloud: A CPAs Travel Guide“, which details the transition from having your IT hardware on site to using a hosting company like Abacus Next, and then the eventual move to browser-based SaaS applications.
While I wrote this a couple of years ago, it has held up pretty well, despite the rapidly changing IT environment. You can download it from the CPA Firm Software site’s page on Cloud Computing