I know this is OLD but here is the deal.
Windows itself is ALWAYS going to take over the master boot drive of the primary sda drive, because microsoft in their infinte stupidty just was written to do that. Its because windows does not recognize ext3 or 4 partiions as valid. It knows they are there but it does not offer to boot them for you.
So if you ever reinstall windows from scratch then your faced with using EasyBCD and creating a Grub2 entry for windows boot loader, in order to get back to your Linux.
Using Easy BCD you were able to get windows boot manager to load your Linux (Any Linux) from the proper hard drive.
That part is very easy and EasyBCD handles it fine.
Now as described you get GRUB to become the bootloader by doing
grub2-install /sda which puts it onto the windows hard drive (the bootloader is directed to the Linux other partiton or hard drive and into the grub menu.
and grub-update has grub go out and scan for any additional bootables such as another Linux and add that to the grub menu. Triple booting if you need that to occur.
Now when you reboot your going to be faced with the Windows 7 loader or whatever it found.
So you choose Windows loader t, and then you will get Windows boot menu, which is wasted cause you dont need it anymore.
However, do this. Boot into windows, run the EasyBCD program, and just remove the Linux boot entry.
Then tick on the skip boot menu down at the bottom, and that is all. DO NOT remove Easy BCD and do not reinstall it either.
Now when you reboot, you get GRUB menu, and choices, but when you pick Windows you will NO LONGER get any Windows boot menu it will just load windows just the way you want.
Problem solved. If you image the drive, you will not need to reinstall grub again, if the imaging software is good like Acronis or Macrium Reflect it will just put back the MBR and direct it to your Linux GRUB and everything is cool.