Wrong forum... you havent got a success story yet
Almost all linux related stuff is GPLed, which basically means the source code is free to be adapted, as long as you provide your changes with compiled versions of your tweaks.
Try running Open or Star Office on your windows machines first, and maybe a different browser like Mozilla or Opera. This way you can find if you need a rare feature which isnt implemented quite yet if any, and your staff can adapt to linux programs while still using windows.
Read a lot, and try running a few test stations with an easy linux distrobution to get used to the differences. I suggest Mandrake 9.1 or maybe RedHat. Both should be a matter or booting off the cd and clicking through the installation process.
After an hour or two you have a fully working system, all hardware autodetected and configured (unless it only has windows drivers) and a full suite or three of desktop applications at your disposal.