Apple and Gateway have altered parts of their server support programs to give customers more choice, the companies announced Friday, as they battle against server-industry titans such as Dell and Sun Microsystems.

Apple began a new software-subscription service on Saturday for Mac OS X Server, while Gateway has extended the length of time a customer has to return a server.

Apple's new Mac OS X Server subscription service gives users three years of software support, which includes multiple OS upgrades, for the same price that Apple currently charges for a single OS upgrade.

Users Users can pay $999 for the service for an unlimited number of clients, or $499 for a 10-client licence, said Brian Croll, senior director of software product marketing at Apple. No UK pricing is available yet.

A single upgrade for Mac OS X Server currently costs $999 for unlimited clients.

Croll said: "If you think you will do one upgrade over the next three years, then this deal makes a lot of sense. This gives customers one budget item for the next three years."

Croll said the deal could be attractive to Microsoft customers who may be confused by its Software Assurance licensing program introduced earlier this year.

Apple UK is currently offering three years of telephone and email support and on-site hardware service, including both Xserve hardware and Mac OS X Server software, for £762.58.

Gateway meanwhile is allowing US customers to return servers for a full refund after 90 days of working with the system.

Both Apple and Gateway are relatively small players in the server market. Apple's Xserve, which went on sale in May, has attracted attention from users familiar with the Unix and Linux operating systems.