New
#11
Where did you get the Windows 7 DVD? Did you burn it yourself?
Did you initially boot from the DVD ("press any key to boot from CD/DVD" at bootup) or run it from the previous OS desktop? You said you might have selected "Upgrade" so it would have been run from the Vista OS in that case.
Do you still have the ability to boot into your Vista OS? If so, you can extract the DVD to the desktop, then run Setup to attempt your Upgrade or Custom clean install.