Windows Vista SP1 (Service Pack 1) is designed to improve Vista's performance, reliability and security. And even though Microsoft hasn't publicised the change it also alters the way Vista's search works, allowing you to substitute an alternate search tool of your own for the one built into Windows.

In this brief review of SP1, we'll take a look at those changes to Vista search, as well as the installation process - and an SP1 bug we found that may be specific to our test machine.

Microsoft has issued a PowerPoint presentation and a white paper about SP1, which is now in the hands of about 12,000 testers. But nowhere will you find any mention of the change to Vista's search function. That may be because Microsoft didn't necessarily make the change willingly; it comes as an extension of the company's 2002 antitrust settlement with government regulators.

See also: Windows Vista review

With SP1, third-party search technologies - think Google Desktop Search - can now be easily integrated into the operating system and used as the default search engine. And it's a change that's apparent as soon as you click the Start button. The search link, which was on the right-hand side of the menu pre-SP1, has been taken away. If you want to search from the Start menu, you'll now have to use the Start Search box. Otherwise, you can use the Search box embedded in Windows Explorer.

In a smaller cosmetic change, when you enter a search in the Start menu search box, and results appear, the names of the links to additional searches have changed, from 'See all results' pre-SP1, to 'Search Everywhere' in SP1. The 'Search the Internet' link, however, remains unchanged.

See also: First look: Windows Vista SP1

Click 'Search Everywhere' and it launches your search results inside your default desktop search program. If you haven't changed the Vista default, the desktop search program will be the one built into Windows Vista, called Windows Search Explorer. If you have changed it, for example to Google Desktop Search, you'll see the results in that search tool.

When you install a third-party search program such as Google Desktop Search, you use that program's normal configuration feature to make it your default search tool. However, in SP1, you can also switch back and forth between the programs you want to use as your default. Choose Start, Default Programs, Set your default programs, and you'll see a screen that allows you to change which search tool to use by default.

In addition, if you choose Start, Default Programs, Associate a file type or protocol with a specific program, you'll see a new entry in the protocol section, called Search. Use this screen to configure what program opens when you click on a file that uses the Windows Search protocol.

For details about changes SP1 makes to search, see this Microsoft Knowledge Base article.

For more information about the Windows Search protocol, see this separate Knowledge Base article.

Microsoft has made some smaller cosmetic changes to Vista as well in SP1. The Disk Defragmenter (Control Panel, System & Maintenance, Defragment your hard drive) now lets you choose which volumes to defragment.

In addition, if you use BitLocker for encryption, you can also choose which drives to encrypt.

Vista SP1 aims at performance and stability improvements, including faster browsing of network shares. On our test machine, however, the beta unaccountably won't allow us to browse to another Vista PC on the network. We can browse XP machines with no problem, but not to another Vista PC. Odder still is that we can make a remote desktop connection to take over the other Vista PC using remote control, but can't browse the PC using Windows Explorer or the Network Map.

On our test machine, installation of SP1 went smoothly, if slowly; it took about an hour and fifteen minutes on a 1.83GHz Core Duo laptop. The machine rebooted several times, and did so automatically, requiring no intervention after installation began.

The bottom line on SP1? Considering that it's still early beta, it's tough to know how much of a performance improvement it will offers users when it's released early in 2008. The only significant interface change is to the search function, and that change will affect you only if you decide to use a search technology other than Windows' built-in search.