I would take it one computer at a time to get used to the software in a normal work day. Do you have other people working for/with you? They will need to get used to the switch in software also.
For most distros there is usually a simple control panel similar to that used in Windows so getting Linux on the LAN is quite easy.
As a web designer I could only switch one of our two computers over to Linux. This is giving me time to learn new skills but I still need Windows to run proprietry software, especially Internet Explorer, Dreamweaver, and Actinic. I will be trying out WINE soon to see if I can run all that in Linux.