Woody Leonhard of Infoworld summarizes the current state of Microsoft KB 2919355, the ambiguously-titled 'Windows 8.1 Update' (not to be confused with the update _to_ Windows 8.1).
In short: Microsoft has frozen two discussion threads on KB2919355 issues (after 103 and 116 pages of comments), and updated the Knowledge Base article with workarounds for seven major errors... some of which don't work.
In last week's Patch Tuesday, Microsoft changed their deadline for this Update until June (formerly they were requiring all Windows 8.1 and Server 2012 systems worldwide to have installed the Update in order to receive new patches).
Meanwhile, if you run a WSUS server, you may notice that the package for KB291355 (last reissued for the third time on 6 May) was apparently silently reissued over the weekend with a new release date of '15 May 2014', but there's no indication of any software updates in the KB article. The article revision number, however, now stands at '21.0'. Yes, twenty-one revisions. With no changelog.
Anyone else with interesting stories about your deployment issues with this Update?
XP doesn't support 64 bit. Check-mate.
Windows XP x64 Edition [wikipedia.org]
Granted, everybody I've heard from say it sucks, and technically no version of XP is supported anymore, but hey.
I knew about that version :) I tried it once, it sucked so hard I consider that bringing that in an argument as unfair :P (try finding drivers for it, for example).