Vista's SP1 was expected to solve a lot of problems; instead, it caused even more trouble. Here are fixes to some top complaints, from a Windows Update that won't update to endless reboot loops.
When Microsoft rolled out Windows Vista Service Pack 1 to millions of users, people had king-sized anticipations about what SP1 would do for their systems. Sadly, for some people, that eagerness turned into an imperial-sized disgust at what SP1 did to their systems. Sometimes SP1 wouldn't install correctly; sometimes it wasn't installed at all; and sometimes it left their machines far worse off than before.
I'm going to profile some common disaster scenarios that crop up with Vista SP1 and talk about what can be done in each case. The vast majority of the problems that crop up with SP1 can be solved with a little care and diligence. Even if you have to completely reinstall, you can usually do so without torching your data.
When SP1 Isn't Offered At All
One of the first problems that people reported with Service Pack 1 was that they weren't being offered SP1 for download through Windows Update in the first place. If they wanted to install it, they had to obtain and apply it manually.
Knowledge Base article KB948343 goes into detail about why this might be the case, with one broadly cited reason being a series of conflicts with a few hardware device drivers. Most of the drivers are audio components by Realtek, SigmaTel, and Conexant, which are often found as embedded devices in a system's motherboard. After people reported SP1 caused serious problems with these drivers, Microsoft suspended automatic distribution of SP1 to any machines that had those drivers until newer versions were installed.
SP1 is usually offered along with the usual crop of Windows Updates, but if it isn't, it may be a sign of a blocking driver.
Common sense would say that if you wanted to get SP1 delivered automatically but didn't have an update for one of the offending devices, you might be able to fix the problem by turning off or removing the device and deleting its driver. In my case, I have a Dell XPS system with one of the offending drivers, but disabling the device in question and unloading the driver didn't cause SP1 to be offered to me. I later suspected this may be due to some of the audio driver's control panel software still being present in the system.
If you clean out the drivers and still don't have SP1 offered to you, go for the monolithic download. This obviously works best if you have the bandwidth for it -- be sure to get the proper edition, either the x86 or x64 version. Slipstreamed media may also be available from PC manufacturers for a nominal fee and Microsoft does sell a separate SP1 disc (available from NewEgg, for instance), but only along with the purchase of an actual Vista OEM disc.