I think I know, but how do you install full oem over an existing drive? From what I'm reading upgrading to Windows 7 Home Premium might not be ideal for me. So if I order the OEM version and want to install it on a drive or two drives in raid 0 that I have Vista on, don't I just install the disk and it then give me the otion to over right or delete the existing operating system and install Windows 7? It's been a few years since I've done this.
The autounattend.xml file CAN be used, but doesn't HAVE to be used. It's created by the hardware vendors to automate the installation on their systems.
When you boot from the Windows DVD, you'll have an option as to which disk and partition you want to install the OS in. There an "advanced" option that lets you delete and create partitions, so you can use it to delete the old Vista partition and create a new, empty partition for installation.