Customers will gain an option of purchasing client-access licences (CAL) on a per-user basis, said Bob O'Brien, a group product manager in Microsoft's Windows server division.
Under existing terms, customers need to buy a CAL for each device that accesses the server.
O'Brien said Microsoft made the changes to give customers flexibility or allow them to take a mix-and-match approach of both per-user and per-device CALs.
"You can pick a combination of both," said Gartner analyst Alvin Park, "but you have to keep track of them."
The per-user option is expected to benefit companies that have employees accessing Windows servers from a number of different devices, such as workstations, laptops and personal digital assistants.
The per-device option, however, would work better for factories with numerous workers visiting the same kiosk or call centre workstations used by more than one employee.
Another licensing change Microsoft will make alongside the release of Windows .net Server 2003 applies to companies that expose a Windows server to the outside world. A new "External Connector" option will replace the existing "Internet Connector" licence that customers bought when they ran a Windows-based Web server.
O'Brien said the clarification is being made to account for business-to-business scenarios in which a company might want to give its business partners access to a Windows server via an extranet. The External Connector cannot be used for people who are employees or who "look like" employees, such as contractors or consultants.
For servers exposed to the outside world, customers will have the option of buying CALs or the External Connector.
A third licensing change will affect users of Terminal Server functionality. Microsoft will now require companies to have a Terminal Server CAL for all clients, no matter which Windows client version is being used.
Previously, customers using the latest version of the client operating system were granted access to Windows terminal services on the server operating system. But if they upgraded their server operating system and did not upgrade their client operating systems, they were required to buy terminal services CALs.
"Customers could easily find themselves moving in and out of compliance with the licences, which has created a great deal of frustration and confusion for those customers," said O'Brien. "This [change] moves us to a more consistent model."
To help with the transition to the new system, Microsoft will give free Terminal Server CALs to companies that have already bought Windows XP Professional; or have their Windows desktop operating systems under an Enterprise Agreement or the Software Assurance maintenance plan; or complete the purchase of Windows XP Pro before the new Windows .Net Server operating system becomes available in April.
The licensing changes will become apparent to beta testers this week when Microsoft makes available the second release candidate of the server operating system.