To restore the Windows Vista/7 bootloader, you must first boot off your Windows Vista/7 installation DVD.
If you have one of the many OEM computers that didnt come with a Vista/7 installation disk, you can get the same effect with a Vista recovery disk, which you can download for Vista or Win 7.
When you get to the Regional settings, select your Location/Keyboard setting then click next. On the next page you must click on "Repair your computer."
On the next page, if it finds your Windows Vista/7 installation, make sure it is UNSELECTED before clicking next.
Then click on "Command prompt". From there, type in the folowing:
Take out your Vista/7 DVD and hopefully, you will be left with your Windows Vista/7 Bootloader.