Hello, Welcome to Windows7Forums.com
Have you tried the vLite application? It's used for pre-customizing Vista/7 installations.
Download it.. you'll probably need to download the WAIK as well, but afterwards, load up the installation source and you can setup auto-unattended installation from there.. Though I'm unsure if you're able to preset the timezone, it has a large number of feautures.. I'd recommend not touching the image for anything past unattended installation setup as it is designed for Vista and doesn't fly well with Windows 7 images.
vLite - Windows Vista configuration tool