vLite is a tool for customizing the Windows Vista installation before actually installing it.
Windows Vista from Microsoft takes a lot of resources, we all know that. vLite provides you with an easy removal of the unwanted components in order to make Vista run faster and to your liking.
This tool doesn't use any kind of hacking, all files and registry entries are protected as they would be if you install the unedited version only with the changes you select.
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.