Unix, Linux and Windows
As they always do in IT, the rules are changing when it comes to which operating system belongs in which role in the enterprise.
The old formula was Unix on the high-end application servers and database servers; Windows in the networking servers, file servers, print servers and e-mail servers; and Linux on the front-end and Web servers.
The current trend away from Unix/RISC toward more economical x86 architectures opens the door for all-out war between Linux and Windows for a bigger chunk of the server market. But you can bet that Unix will not go without a fight and may never disappear.