Theres a whole truckload of stuff dealing with Windows 7 automated installs on MSFN.org. Its not all in one place and you will have to read through a fair amount of info. Maybe you should check out their forums and go through the Windows 7 unattended sub forum. Lots of stuff there.
Ever considered installing from a "custom" windows installer? They are built for exact reasons like these. There are no legal issues so long as you own your own copy of it.
EDIT: Sorry, I know that it is not very helpful now, but a custom windows might be a good idea next time you reinstall