The screenshot shows that your System Active MBR has been derailed to the Music data partition. Assuming you have the 64 bit OS plugged into DISK1 now, you would boot the 64 bit DVD Repair Console or Repair CD to mark Music inactive, Mark Windows 7 active, then run Startup Repair up to 3 separate times with reboots until Windows 7 starts.
I am guessing (again, since you don't tell us any of this) that you installed 32 bit to another drive because you don't have a 64 bit install DVD to boot its Repair Console to do these repairs. So you need to burn a 64 bit Repair CD after downloading it from here: System Repair Disc - Create
Now boot the 64 bit DVD Repair console or Repair CD, press Shift F10 at first screen, type in Command box:
SELECT DISK 0 (confirm this is data drive #)
SELECT PARTITION 1 (confirm this is Music partition #)
SELECT DISK 1 (confirm this is Windows 7 64 bit HD #)
SELECT PARTITION 1 (confirm this is Windows 7 partition #)
Now boot back into 64 bit Repair CD or 64 bit DVD Repair console, click through to Recovery Tools list to Run Startup Repair up to 3 separate times with reboots until Windows 7 starts. Startup Repair