Microsoft Corp. said Wednesday it will release a major package of updates and fixes for the Windows Vista operating system in the first half of 2008.

The company said a "beta" test version of Service Pack 1 will be released "in a few weeks to a moderate-sized audience." The SP1 beta includes updates Microsoft has already made to the operating system it started selling to consumers at the end of January.

In the past, some of Microsoft's business clients used the release of a service pack as a sign that a new operating system was stable enough to install. Analysts have said Vista seems more reliable out of the box than past versions of Windows, and that businesses need not wait for the service pack.

The service pack fixes some common problems that cause computers to crash or freeze, Microsoft said, including compatibility problems with some newer graphics cards, external monitors and printer drivers. Microsoft said it also fixed some problems users had with putting their PCs to sleep and waking them up again.

The company said SP1 is also expected to improve battery performance, increase the speed of copying files and help Internet Explorer run faster on Vista.

The Redmond, Wash.-based software maker said SP1 also brings several security improvements.

Microsoft said it expects to release Service Pack 3 for Windows XP, Vista's predecessor, in the first half of 2008 as well, but in a statement added that it "should not significantly change the Windows XP experience."