I have some good news about a problem I described a while ago, concerning attempts to install SQL Server on XP SP3 machines. The install would fail because XP SP3 places MSXML files under system protection, and so attempts by installation programs to update them would fail.
I posted some ugly workarounds, and at least one slightly better workarounds emerged from users who visited the blog post. While the kludges worked, they were a bit messy, requiring you to manually uninstall the MSXML components, and even then it wasn't always enough. A much easier workaround involving editing the registry has existed all along, but it was solely in the hands of the engineers over at Microsoft Product Support Services (PSS), who decided that modifying the registry was far too dangerous and sophisticated for mere SQL Server users running XP, and so they prevented the registry fix from being publicized (either in a Knowledge Base article or, while waiting for said article, on an unofficial site like this one). Instead, they decided that their "solution" would be to require users (or at least, users who figured out that there was an easier fix they could obtain) to call support, lay down the close to $300 to open a support case, get the fix, then push for a refund. (Unless you were a Microsoft Partner, in which case, you could allegedly get the fix from the unfinished internal Knowledge Base article via the Partner KB.)
(All the while, there are over 1,400 KB articles, in English alone, that mention "regedit.exe" according to this Google search.)
Anyway, enough complaining; on with the good news. After much pressure, apparently mostly from yours truly, the support folks over at PSS have reluctantly agreed to make the registry change public, in a forthcoming KB article. I do not have an exact delivery date for you, but I was told that it should be available by the end of the month. If you see it before I do, please post here or send me e-mail (<firstname>.<lastname> @ gmail.com).
Hopefully it does not turn out to be a cruel April Fool's joke.