The big news about Windows Vista SP1, whose Release Candidate became public a couple of days ago, is its improved performance and reliability, thanks to over 400 hotfixes and updates. However, that's only part of the story.
New Hardware Support
Windows Vista SP1 includes
Support for GPUs supporting DirectX 10.1, which improves 3D rendering
A new exFAT file system supports large file storage in flash memory and consumer devices
Know a Windows Vista newbie? Help a new Vista user get up to speed with Mark's book Maximum PC Microsoft Windows Vista Exposed. It's a great introduction to what's new and different in Windows Vista, and it's available from Amazon.com and other fine bookstores.