Choice Guard does a simple task of writing a value into the Windows 7 registry and protecting your default settings. During installations, if opted for, it is responsible for setting the users homepage and search defaults.
Several software products install registry keys or services which prevent you from changing the registry key.
Choice Guard looks for the presence of such services which may be preventing the user from exercising his choice from being carried out.
It then finds a way to negate their effects and set the search defaults, as chosen by you.
It is installed while installing any Live products. During installation, it asks you if you’d like to protect your settings. It does this only once.
Its installer, by the way, can be found in C:\Program Files\Common Files\Windows Live\.cache\b45fad1d1c9b112 folder.