If you think your employees will experience a significant change, you should consider a short-term "pilot project" before a full implementation. For example, your business might not have e-mail, Internet connectivity, server-based faxing, or an electronic accounting package today.
You might assign three or four employees or just your accounting department to try out these new features on a server configured the way you expect the system to be deployed in the entire business. As these few employees learn the system, you will learn how this change might affect the rest of your employees. Once you're satisfied with the change in your employees' behaviour and the configuration of the system, you can start adding employees incrementally or over the course of a weekend.