An IT manager who is planning for this move, presenting a case to upper management, budgeting, and trying to get the invoices printed by the end of the week needs to know!
Staying with Windows carries risks that IT managers need to understand. In 2000, guitar-string maker Ernie Ball was raided by the Business Software Alliance, under a program called "Nail Your Boss". A subsequent audit found a few dozen unlicensed copies of programs. Ernie Ball settled for $65,000 plus $35,000 in legal fees. The BSA also put the company's name on the evening news and featured it in regional advertising as a warning to other companies.
Ernie Ball responded by removing all of its Microsoft software within six months, substituting Red Hat Linux, Open Office, Mozilla, Evolution, and some proprietary software. Ernie Ball's CEO, Sterling Ball, says that the switch cost much less than $1200 per station.
If you want fire up a Linux system as a test case, Knoppix makes a CD that you can boot directly without reformatting your hard drive.
Red Hat makes the most widely-sold Unix distribution in the world. Red Hat is a pioneer in the area of making systems easy to upgrade. A new package called yum can upgrade RedHat systems between major revisions.
Suse has recently been acquired by Novell and has won several large contracts, including the city of Munich. Suse differentiates itself from RedHat by targetting enterprises as opposed to home users.
Debian prides itself on having an easy installation process, easy upgrades, and a thoroughly integrated desktop environment. Debian's distribution comes with more than 8710 packages of various kinds of software. Debian's website is very professional but refreshing in that it has obviously not been crafted by Madison Avenue image-polishing spin-doctors. For example, the latest list of security alerts is posted right on Debian's home page! The home page also includes a good introduction to the ethos of the free software community in general and GNU/Linux in particular.