Did you buy a Windows 7 upgrade version to use on this computer? If so boot it to Clean Install Windows 7.
If it fails, reboot into the DVD, press Shift + F10 at the first screen to open a Command Line, run Diskpart Clean Command
then try the install again.
If that fails post back the exact step where it fails in Clean Install Windows 7
and the verbatim error message.
If you don't have a legit Windows 7 Upgrade DVD with Product key then reinstall Vista as I suggested in my last post. If you have the Product Key but no DVD we can provide it for you.