Linux is free, Linux is maintained by the open source community, and Linux simply isn't Windows.
Many see Linux as being more stable than windows OS, although I do find the more junt you install on Linux, the more unstable it becomes.
Most major programs you use in Windows, you can find open source equivalents in the Windows community.
OpenSuse is my favorite Linux distribution. On a major brand of hardware, like a Dell desktop, installation typically is seemless.
On the other hand, there are
alot of people that still don't know Linux, and are afraid of it. It's alot easier finding administrators that have an MCSE or MCP designation, than it is to find certified Linux professionals. On the other hand, Linux knowledge always looks great on a resume, especially in the Java/Sun/IBM community.