Windows Vista SP1 is an update to Windows Vista that, along with improvements delivered to users via these other channels, addresses feedback from our customers. In addition to previously released updates, SP1 will contain changes focused on addressing specific reliability, performance, and compatibility issues, supporting new types of hardware, and adding support for several emerging standards. SP1 also will continue to make it easier for IT administrators to deploy and manage Windows Vista.
- roll-up of security and hot-fixes
- File size - NOTE: not required space - 65mb (update) to 450Mb (stand-alone)
- improvements (heaps) - reliability, security, remote management, interoperability
summary (bits I have picked up on\like):
- Support for Unified Extensible Firmware Interface
- Improves the success of peer-to-peer connections
- SP1 addresses issues many of the most common causes of crashes and hangs in Windows Vista
- Improves the performance of browsing network file shares by consuming less bandwidth.
- Improves power consumption when the display is not changing by allowing the processor to remain in its sleep state which consumes less energy.
- Addresses the problem of the Video chipset (VSync interrupt) not allowing the system to stay asleep
- 25% faster when copying files locally on the same disk on the same machine
- Improves the copy progress estimation when copying files within Windows Explorer to about two seconds
- Includes improvements to Windows Superfetch™ that help to further improve resume times, in many environments
- Improves security in smart card scenarios
More information here
Release candidate here