I wouldn't question whether all the Windows7 Media that you have tried are genuine or not
but go on to suggest that it is time for you to straight away install the Integrated Windows7 SP1 by downloading the appropriate ISO for the version you have a valid Product Key
. Go through this
thread to help you out on this.
(What I have understood is that the media you used did boot and install went upto a certain stage - may be till the first Windows 7 screen appearance - whereupon it failed and to that extent your title is misleading. "Windows 7 fails to install" may perhaps be more appropriate. Sorry if I have misunderstood anything.
Did you try on another HD as Gregrocker suggested? Try both SATA as IDE/default setting (my suggestion) and AHCI in bios setup (Gregrocker's suggestion).If it fails to install on a new HD too, then I would certainly say that something is wrong with all the Windows7 media that you are trying. This is fortified by the fact that you are able to install Windows XP, which may be genuine.)