This is the software publisher's description.

Windows Vista from Microsoft takes a lot of resources, we all know that. So here is the tool for easy removal of the unwanted components in order to make Vista run faster and to your liking. vLite can also create the bootable ISO and apply the tweaks directly.

This tool doesn't use any kind of hacking, all files and registry entries are protected as they would be if you install the full version only without the components you select for the removal.

It configures the installation directly, before the installation, meaning you'll have to remake the ISO and reinstall it. This method is much cleaner, not to mention easier and more logical than doing it after installation on every reinstall.