Iron, I think you should disconnect your vista drive (Remove all cables) and leave only the empty drive to install win 7 on.
boot your system and immediately start tapping f8 to get to bios boot manager and select your DVD Drive (I you put the DVD in) and see if it will boot.
If the DVD does not boot then you should take that DVD to another machine and see if it will boot there.
If the DVD does not boot on any machine, then the DVD is no good.
If the DVD boots on your machine, you should be able to complete the install and get a bootable Hard drive. If it installs, remove the DVD, do not connect other drive, and see if it will boot from your newly created hard drive.
If it boots, you are good to go. If it doesn't then there is another issue.
Please post back