Microsoft has warned Windows users that it will soon turn on automatic distribution for a major search update that requires machines to re-index all local data.

In a post added to the Microsoft Update team's blog Friday, the company said it is planning to release Windows Search 4.0 to Windows Update "sometime in late July." Windows Search 4.0, which went final in early June, sports stability and reliability improvements, Microsoft said at the time, and gives more control to enterprise IT administrators over users' access to and use of search.

Windows Search 4.0 will be offered to Windows XP users as an optional update, Microsoft said; anyone running the older operating system must call up the Windows Update (WU) service manually, then select the search update.

Most users running Windows Vista Service Pack 1 (SP1), however, will find that the search update downloads and installs automatically, as it will be listed as a recommended update for that OS. "If a Windows Vista user has set their machine to automatically install updates, Windows Search 4.0 will automatically install on PCs running Windows Vista SP1," said Microsoft.

After installing, Windows Desktop 4.0 will completely re-index the user's data, a prerequisite for executing fast local searches. Depending on the amount of data on the machine and Windows Desktop 4.0's settings, re-indexing can take as long as several hours.

Microsoft, however, downplayed the performance drag of the update's re-indexing, claiming that the new tool is intelligent enough to free up other resources when they're needed. "Windows Search will release most of the requested resources and slow down the indexing process as soon as it detects mouse or keyboard activity, or when another application requires computer resources," Microsoft said.

Enterprise administrators armed with System Center Configuration Manager (ConfigMgr) 2007, or the older System Management Server (SMS) 2003, have been able to deploy the search update since June, but businesses that rely on Microsoft's free Windows Server Update Services (WSUS) will see it hit automatic deployment when the update reaches Windows Update. WSUS administrators can block the automatic distribution of the update using a batch script that Microsoft provided in a support document. The batch file doesn't bar users from downloading Windows Search 4.0 from Microsoft's download site, however.

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