Can't Install Windows 7 after Windows 8 install

Ok so I feel pretty stupid but for the life of me can't figure this out. So I installed Windows 8 on my Dell Inspiron 6400. It was running Windows 7 and I figured I would give 8 a try (huge mistake). So now I am trying to get back to 7. I tried booting to my Windows 7 USB and it just boots to Windows 8 install which I find pretty odd. So I format the drive and try to reboot to the 7 install but same thing. So I research online and see talk about secure boot and UEFI but this is not an option on my laptop so did not help. So then I try to create a dual boot to see if that will let me install so I can wipe the 8 partion. But again no luck. So I was thinking of breaking out my SATA adapter and hooking that drive to my other laptop to try and wipe the drive that way and trying again but was wondering if anybody could give me any other ideas or let me know if I may be overlooking something as I don't feel it should be this difficult.

If you can't boot from Win7 USB install media make sure you select USB device under LEGACY boot options. Press F12 at bios post

You said that even after you formatted Windows 8 the installation media still boots to Windows 8? If so then you didn't format the partition or wipe the drive correctly, obviously. It's always best to wipe the drive of all boot code. I will walk you through doing this in sequence that covers all installation failures.

You know for sure you don't have UEFI BIOS? Did you see EFI boot options when booting the installation media?

Work through the steps to Troubleshoot Windows 7 Installation Failures - Windows 7 Help Forums

Confirm the installation media, if necessary replace it and write to stick with tool - all provided in Step 1 of Clean Reinstall Windows 7 which are the steps you should be following to get and keep a perfect install.