Yesterday thanks to CarolFromHazlet's link to TechSpot (one of my favorite websites, btw) I did get Quicktime v7.7.80.34 installed on my old WinXP box without any problems. And unlike sooooo many other problem threads here at "iTunes for Windows", iTunes 10.4.0.60 runs just fine for me (whew).
As to "... what's going on..." with the Apple download webpage being now reverted back to old QT v7.69.80.9, I can only hazard some guesses- None of which are complimentary to the "Geniuses" at Apple.
A year ago (& earlier), whenever I'd launch (then-current versions) iTunes and/or QuickTime, they would lockout ALL Windows graphical interface functions (mouse freeze, no screen draws, static clock display, etc.), as I reported in this forum -> I never got ANY useful solution from Apple or other users. Fortunately WinXP hadn't crashed & I could still do controlled shutdowns vis keyboard (Start>Shutdown) albeit with NO actions diplayed on scree. For that reason (& several more important reasons), I subsequently did a full reformat + re-install of WinXP (+ the hundreds of Windows updates), re-installed many programs & restored data files, and now that XPSP3 box runs great. That's some consolation for the DAYS I had to spend rebuilding that PC - Thanks alot Apple Geniuses.
Windows XP Pro 32-bit SP3 * iTunes v. 10.4.0.80 * QuickTime Player 7.7..80.34, dual-boot PCLinuxOS2011