KB937287 -- "configuring updates stage 3 of 3. 0% complete"
A few people have run into a problem after installing KB937287, of the pre-requisite updates for SP1. The solution for this issue is available in KB949358. If you have any problems following those instructions, please call 1-866-PC-Safety (1-866-727-2338). This phone number is for virus and other security-related support. It is available 24 hours a day for the U.S. and Canada. Should you call that number, be sure to tell the person who answers that you are calling in reference to a Windows Update issue.
Program Loss of Functionality after Installing SP1
Although most programs will continue to work as expected after you install Windows Vista SP1, some programs were reported as resulting in a loss of functionality after SP1 was installed. The programs and the link to the vendors' solutions are available in KB935796.
Windows Genuine Advantage (WGA) Changes to SP1
With SP1, "Reduced Functionality Mode" (RFM) has been removed and replaced with a notifications-based experience. For a full report and screen captures of what this entails, see Taking the next step with Windows Vista SP1.