What is the difference between per seat, per server, and per processor?
The Per seat licensing model refers to the total number of computers allowed to connect to the service on that machine. Each connection is called a Client Access License. In per seat mode a single CAL for each workstation can be used to access multiple servers in per Seat mode. This is usually the most economical option In Per Server licensing, each CAL is dedicated to that specific server (think of this as concurrent connections). In per Processor mode, no CALs are needed to connect to the server. The right to access the server is covered by the (more expensive) Software License itself. Refer to http://www.microsoft.com/licensing for more information.
