I have not used Linux in any sort of business network environment. This opinion is based on my experience in using it at home, and working with a few other Linux explorers:
1. Make sure there are applications that will have the functionality you need. Generally there are programs that will do anything that can be done in Windows. Check the various Linux forums for sources for these.
Check here for one such office suite.
2. It will take a while for your users to adapt to the slightly different look and feel. There are many different front ends for Linux such as Gnome and KDE. More info here.
3. You will probably want a few windows machines on your network to act as “can openers” for the odd file that can only be opened in a Windows application.
4. Join Linux forums, they are where most of your support will come from. here are a few, but there are MANY out there…
5. when shopping for hardware such as printers and scanners, make sure there are Linux drivers, most have Linux drivers available, but some do not have that info right out in the open. Again check the forums for support. There are sites like this to help you along in this area.
6. Having at least on person on your staff who is a Linux-Fanatic (check for the Tux penguin tattoo over their heart…) will be a great help.
I would just add that sometimes technical support is an issue in Linux environments. Depending on what flavour of Linux you are running, you may not be able to just pick up the phone and call someone for help.