Type in Format disk into search box in windows 7 . ( create and format disk partions) shoud come up click on that. A grafhic of your drive should come up You should have partitons of where the OS of windows 7 And Vista on the drive. Click on the Windows 7 partion make sure it is the one you want with Win 7 in it. There will be a small partion on the drive that will be drivers and win & kerrnal leave it alone. Right click on the Win 7 drive.It should get slashes though it. put your mouse on the slashed drive and left click.
Chouse ( change Letter and path) switch letter on your two drives.
See if it boots to windows 7
( win 7 should have created its own partitions when it laded in on install )
Edit this is the hard way