Windows 7: IE9 and add-ons

I generally use Firefox. I was trying to see how IE9 has improved. During the set-up, I was trying to install some add-ons. They would not install stating the a file/folder does not exist. These are different for each. I tried to reinstall IE9 and install from scratch. The installation could not proceed stating that the installed IE9 is more current, IE9 cannot be removed as I tried many tricks.

Any ideas?

IE9 was added to the list of "Installed Updates" in Windows Update. You can also get to it from Programs and Features>>"View Installed Updates". You can uninstall it from there and you will automatically revert back to IE8.