I recently blogged about my trials and tribulations with installing Vista Service Pack 1 on my desktop computer. To put it mildly it did not start out well. I blue screened,for the first time with any Vista machine I've worked on and was only able to salvage the computer by starting in safe mode and reverting to a restore point. This is the point when I start looking for help from Microsoft.
Fortunately it came,and it was quite good. I emailed tech support and they got back to me the next morning. The suggestion was to do a upgrade install (Repair) of my system. The "Problems and Solutions"log had informed me I was using a beta version of Vista when I needed a retail version, even though I had bought one when I built the PC last year. This indicated to the tech support person that it was most likely corrupted system files. She also suggested I install SP1 in a clean boot mode, which is done by turning off all startup items using MSCONFIG. In short it worked great, and I actually notice a faster machine with SP1.
File copy after SP1 is also considerably faster and the machine does have a certain pop to it that it didn't have after doing the repair install, and had turned off the startup items in the System Configuration.
So Vista SP1, it was worth the initial headache, if you have Vista and it's available when you check for available updates, do it.