Source: http://lifehacker.com/5635089/install-itunes-10-without-the-extra-bloatware
Windows only: It's no secret that the iTunes installer loads up your system with extra components you probably don't need, and there's no way to opt out—unless you crack open the install file, that is.
Over at ZDNet, Windows expert Ed Bott shows how to install iTunes components piece-by-piece, starting with extracting the components from the installer so that you can install each piece separately—he also walks through exactly which pieces you'll need to install depending on which iPod model you have, or which features you are using. It's a great read for anybody stuck using iTunes on Windows.