you need to have at least ONE partition marked as active before it's bootable with W7.
If you have s system "Reserved" partition then flag that as ACTIVE. If this doesn't exist mark the "C" partition as ACTIVE. Just setting these as PRIMARY isn't sufficient.
Now if on boot it still gives you a BSOD then just use the recovery console -- boot from the W7 install media and choose REPAIR SYSTEM. It won't change any existing data.
To reset the partitions you need to user a bootable partition manager like GPARTED. Just boot the media and follow the instructions.