The pain that is the Vista Service Pack 1 update starts for the lucky (or unlucky) enough to be using Vista. While enterprise customers as well as other select groups have already had access to Vista for some time, customers that were not able to get early access will finally able to download it starting later today.

Service Pack 1 is not without its pitfalls in the installation process. Service Pack 1 for Vista, for example, will refuse to install on a system that has a driver which Microsoft has determined can cause an issue either before, during, or after the installation.

To be on the safe side, you should likely check and make sure that you are running all of the latest drivers for Vista prior to trying to install SP1 on your system. This, of course, can be a problem in itself because from what we are hearing, some of the updated or upgraded drivers have yet to be released; so even if you are running the latest drivers on your system you still may not be able to install SP1.

Microsoft will be offering the SP1 update in two different ways, which are as a standalone package that you can download and install on your system or as an optional update via Microsoft’s Windows Update Service. Based on our experience during the beta process, you are likely to have a better time of getting it installed if you elect to download the standalone installer package rather than trying to deploy SP1 via Windows Update.

For those curious, the installation process of SP1 for Vista can take anywhere from between 20 minutes to over 1 hour to be installed depending on the system speed, configuration, and other factors that can influence the installation process. Microsoft has created a new version of Windows Vista that will already have SP1 integrated into it that should be showing up on dealer shelves shortly.

SP1 for Vista is focused on fixes and improvements to the performance of Vista, so don’t expect any real changes to the look and feel of Vista. Once the installation is complete, the SuperFetch and ReadyBoost caches are deleted of all cached information, so performance once SP1 is installed will be a little less at first until these caches build back up.

As for performance improvements after installing SP1, our general feeling is that we noticed some improvements in a couple of areas, but as a whole we didn’t see anything that really knocked our socks off. Given that the focus of SP1 was more targeted toward bug fixes, this was to be expected. In the end, we can say that most users will benefit from the installation of SP1 for Vista and at this point we see no reason not to recommend it as long as you can get it installed.