itunes.msi is missing

First, screw you iTunes.
Second
If you get an error that is asking you to locate an itunes.msi file, don't worry.  Its a simple fix.
There are places that tell you to run some MS installer program that will repair it, and the link to it is the dumb Fix It handyman that they have.
(continue at your own risk)
A quick fix would be going into the registry, and searching for itunes.msi.  When you find the key that has it, delete the folder that its in.  The folder will appear open in the left pane.
Hit F3 to find the next instance, rinse and repeat (delete the folder containing the reference to itunes.msi)
Then search for quicktime.msi, and continue the key deletion.
Once you're done, got to www.itunes.com and reinstall iTunes.

One instance after doing this, I got "apple application support error 2"
 but this fix worked for me:
https://discussions.apple.com/message/17718475#17718475
Download and save a copy of the iTunesSetup.exe (or iTunes64setup.exe) installer file to your hard drive:

http://www.apple.com/itunes/download/

Download and install the free trial version of WinRAR:

http://www.rarlab.com/

Right-click the iTunesSetup.exe (or iTunes64Setup.exe), and select "Extract to iTunesSetup" (or "Extract to iTunes64Setup"). WinRAR will expand the contents of the file into a folder called "iTunesSetup" (or "iTunes64Setup").

Go into the folder and doubleclick the AppleApplicationSupport.msi to do a standalone AAS install.