Apple computers are gaining in popularity, but Windows-based PCs are still by and large the "norm" when it comes to personal computing.
By contrast, Windows-based PCs are usually more easily upgraded (more RAM, bigger hard drives, faster optical drives, etc.), have more programs (both free and for purchase), and are usually cheaper.
Guitar Chord Crash Course 3/4 is a Windows based application that helps users learn chords.
One Billion Chords is a giant Windows based chord directory.