Microsoft has revised its support programme, extending support to its software products past the current 10-year cut-off - but at a price.

The software giant has made its first revisions to the two-year-old Custom Support Agreement program and will now provide mainstream support for five years before charged-for extended support starts for an additional five years.

The customer support program is also being expanded to include more kinds of legacy software, including client-side software. Microsoft will use demand as the basis for its decisions about which ageing software to add. Today the program covers only Windows NT 4.0 and Exchange 5.5, but Microsoft will add Windows XP SP1 when it reaches its end-of-life date in October.

Microsoft plans to price support per device - desktop PC or server - and said the starting price for support contracts would probably be in the tens of thousands of dollars for a pre-determined minimum number of devices. There is no set price list. Instead, support costs will be negotiated with individual companies based on the software and how much of it users have been running.

The Custom Support Agreement program, introduced in December 2004, is designed to prevent users from having to run software that's unsupported and therefore without available hot fixes for known security vulnerabilities. The extension program is designed to give users more flexibility in planning migrations, so they can avoid running unsupported software if migrations get off-schedule or if other issues prevent a timely migration to a new version of software.