Microsoft has released to testers a pre-beta copy of Update Rollup 1 for Windows 2000 SP4. The update rollup encompasses all security-related fixes made to Windows 2000 from SP4 to the time the package ships.

In November, Microsoft said it would ship a collection of critical updates for Windows 2000, rather than issue Service Pack 5.

This is not the first time Microsoft has opted to release an update rollup rather than a full-fledged service pack. A security rollup for Windows NT4 was offered after Service Pack 6a, and Windows XP Update Rollup 1 was issued due to delays in preparing Service Pack 2 for Microsoft's flagship operating system.

Microsoft cites a number of reasons for choosing the rollup, including less of a need for testing, as most of the updates have been available as individual hotfixes. The company also says many of the fixes relate to obscure problems, which are not likely to affect the majority of customers.

"Because every update to Windows introduces the possibility of system instability at the customer's site (for example, an update to one part of the system causes some other part of the system--or an application--to fail), an Update Rollup will provide the maximum utility at the minimum risk of instability at this point in the Windows 2000 life-cycle," Microsoft says.

Update Rollup 1 for Windows 2000 SP4 is likely to finish its beta cycle in late March, with a public release in April, according to testers.