Improvements in reliability
Windows Vista SP1 includes improvements that address many of the most common reasons for which Windows stops responding. Many of the reliability improvements in SP1 are in response to issues that customers reported by using the Windows Error Reporting tool.
Other reliability improvements in Windows Vista SP1 include improvements in wireless computer-to-computer (ad hoc) connections, better peer-to-peer connections, such as using Windows Meeting Space, and many more.
Improvements in performance
Windows Vista SP1 includes many changes that can improve your computer's speed and performance. Here are some of the areas that are improved:
Faster copying or extracting files from a compressed mode.
Better use of network bandwidth when browsing file shares over a network.
Improved performance from Windows ReadyBoost in reducing the time it takes for Windows to wake up from Hibernate and Standby power modes.
Better power consumption when your computer screen is idle for a long time.
Improved logon experience when using a corporate computer, such as a laptop, outside of the corporate network.
Faster opening of large image files.
Improvements in security
You can now use BitLocker to encrypt multiple partitions on your computer's hard disk, rather than just a single partition. Note that BitLocker is only available in Windows Vista Enterprise and Windows Vista Ultimate.
Changes to search
SP1 includes an important change to the way desktop search works in Windows Vista. You can now select a default desktop search service, similar to the way you can select a default search service for web browsers and media players. With SP1, you can now get to your preferred search results from within the Start menu and Windows Explorer.
Changes in memory (RAM) reporting
SP1 also changes how the random access memory (RAM) that is installed in your computer is reported. Before SP1, the amount of memory reported was equal to the amount of memory that Windows was able to use. In SP1, the amount of memory reported is the amount of memory that is actually installed on your computer. If you have 4 gigabytes (GB) of memory installed, you'll now see 4 GB of memory reported by features such as System or Performance Information and Tools in Control Panel. This change can only happen if your computer's basic input/output system (BIOS) is capable of displaying that much RAM.
If you are an IT professional or an advanced user and want additional detailed information about SP1, you can find the release notes, the SP1 deployment guide, and other information at the Windows Vista Service Pack 1 Resources page on the Microsoft TechNet website.