c:\WINDOWS\system32\QuickTime\Uninstall.log

You may need to "clean up" the uninstall a bit first using something like this:

Microsoft's Windows Installer CleanUp Utility:
http://support.microsoft.com/default.aspx?kbid=290301

Maybe I don't see but Quicktime isn't listed in your list. If you are getting that message when trying to install QT then you might be doing something else wrong.

When you launch the QT installer what is the first message you get?

c:\WINDOWS\system32\QuickTime\Uninstall.log

Oddly enough, this one tends to respond better to brute force than finesse.

Rather than trying to uninstall QuickTime prior to reinstalling QuickTime, try doing a standalone QuickTime install "over the top" of what you've already got in there. Here's a link through to the QuickTime installers:

Quicktime 7.1.6 Installers … get the one that doesn’t mention iTunes

I'm now assuming you tried doing a cleanup of you machine?

Here are my instructions on doing a clean install.

1. Uninstall itunes, ipod & QT software from add/remove programs in the control panel.
2. Reboot your PC
3. Re-download the itunes installer and QT and save this installer to your desktop
4. Go to C:\WINDOWS\Downloaded Installations. You should see folders like {06EB3288-C5F4-4C73-8EEE-AC798668FF66}
5. Look in each of these folders for itunes.msi and delete the folder. Be careful to only delete the folders containing itunes,msi
6. Clean out your temp folders, Delete as much as you can in these folders except for the folders Cookies, History, Temporary Internet Files.
a. C:\windows\temp (if one exists)
b. C:\Documents and Settings\{username}\Local Settings\Temp
Sometimes installers will pick up old files or won’t delete their temporary files.
7. Go to http://www.download.com/3000-2094-881470.html and download the regcleaner. Unpack it and run it. This is a nice utility that will delete broken registry entries and create a file with them. This way if it deletes anything needed you can add it back. Note I never had to do this with using it for many years. Also it doesn't list XP but you'll be fine. I run XP on both.
8. Optional: Goto www.safety.live.com Its a MS site that will scan your PC for virues and repair the registry. Some of it is subscription based but there is a free service if you look.

8.5 Reboot your PC.
9. Now try to go and install everything again. I'd do QT first then follow with itunes. Remember to disable virus/firewall/privacy/web accelerators before launching the install.