Is that the thing that restarts your computer to install new updates when you aren't expecting it (usually when you go to bed with a torrent running for a movie you really want to watch the next day)?
no, that's Windows Update. Windows Installer is the .msi packages software comes in. Don't get me wrong, it's better to have an .msi than some ad-hoc executable that probably doesn't uninstall correctly, in fact I'm always reluctant to install software that doesn't have one, but good God are they a pain to make for anything complicated.