The following is taken from a Vista Newsletter - hope it helps:
Where is winnt.exe in Vista?
With Windows NT, 2000, XP etc., you could install the operating system by running winnt.exe in the i386 folder. This doesn't seem to be the case with Vista. I always copied the i386 folder to the hard disk in case I needed to repair corrupt system files later, but I don't know what's going on with Vista. Is there something equivalent to winnt?
The installation process in Vista is completely different from that of previous Microsoft operating systems. That's because the installation DVD actually contains a compressed image of the Vista OS. The install.wim file executes when you run the setup and decompresses the image onto your hard drive. For a more detailed explanation, see
If you've installed Vista Service Pack 1, you can use the administrative tools it installs to create a recovery or repair disc to repair corrupt system files. This creates a "stripped down" version that lets you do a repair without the Windows installation disc. You can create a bootable USB version of the repair disc. Read more about that here: