The installation of Service Pack 1 for Windows Vista is synonymous with the evolution of the latest Windows client, focused on a variety of aspects including the way the operating system deals with the underlying hardware resources. SP1 does bring to the table increased performance, but it also does something much better, it actually "adds" system memory. Following the introduction of the service pack, the operating system will report more RAM than it did as in the RTM build, in various scenarios.

The first example comes from Michael S. Kaplan, Technical Lead on the International Fundamentals team at Microsoft, and is the confirmation of what Microsoft promised that Vista SP1 will deliver to 32-bit machines with 4 GB RAM. Before Vista SP1, previous x86 Windows platforms, including Vista RTM, reported only a portion of 4 GB RAM, keeping in line with the limitations of the 32-bit operating systems to address system memory beyond 3.3/3.5 GB. SP1 changed this for some Vista RTM machines powered by 32-bit processors.

"With SP1, Windows Vista will report the amount of system memory installed rather than just the amount of system memory available to the OS. Therefore 32-bit systems equipped with 4GB RAM will report all 4GB in many places throughout the OS, such as the System Control Panel. However, this behavior is dependent on having compatible BIOS, so not all users may notice this change," reads an excerpt of the Notable Changes in Windows Vista SP1 document.

With SP1, Kaplan's 32-bit copy of Windows Vista Ultimate now reports a full 4 GB RAM, even though, as you can see from the Task Manager screenshot, the operating system can use only some 3 GB. But Vista SP1 can do even much better. The screenshots bellow come from one of our test machines on which we run a pre-release version of SP1. It erroneously and artificially added 14 GB of RAM to a 32-bit system, an otherwise impossible task. As you can see, the Task Manager is not fooled by Vista reporting 16 GB of RAM, and indicates that it can use only 2 GB of memory. The fact is that Microsoft has also had to deal with the Windows Experience Index being modified by the introduction of Vista SP1.

"After you install Windows Vista Service Pack 1 (SP1) on a computer that is running Windows Vista, you may notice that your computer's Windows Experience Index score has changed. For most computers, the Windows Experience Index score does not change after this service pack is installed," the company informed. "Windows Vista SP1 corrects the way that the Windows Experience Index score is calculated for certain hardware configurations. In Windows Vista SP1, the Windows Experience Index score more accurately reflects the ability of the computer to support Windows Vista features. After you install the service pack, this score may drop by 0.1 or 0.2 points."

Windows Vista SP1 is available for download here.