HELP! iTunes will NOT install

Had iTunes on the machine, had to uninstall it for some reason.

Trying to put iTunes back on, so I downloaded the latest version (32bit just like my Win7) directly from Apple, and when I double click on iTunesSetup.exe, the mouse pointer goes busy for a short time, and then NOTHING ELSE HAPPENS.

No errors or any other clues or information.

Here is what I have tried:

-running chkdsks on all drives
-removing all apple software on machine
-removing iPod device from Devices
-trying to install different versions of iTunes or iTunes from different sources
-uninstalling my security and antivirus programs
EDIT: -also did the whole Run As Administrator thing also

No matter what I do, nothing happens. I can see the iTunesSetup.exe process show up in the Processes tab of the Task Manager for one second, before it quietly vanishes again.

What should I do? I NEED iTunes for my iPod Touch.

How can I get iTunes installed?

Sorry, I already tried that also. (with each attempt)

Go it done. The key appears to have been UTTERLY removing EVERYTHING - even going so far as to delete every iTune folder under Users/Local, LocalLow, and Roaming, and Programs Files, and clearing out all Temp files.

Thanks!