If the System Reserved partition was originally there but not reimaged or for any other reason the image isn't marked Active or include SYstem Boot files, then OP will need to mark it Active, boot the Win7 DVD to run up to 3 separate Startup Repairs with reboots to write or repair the System Boot Files to Win7.

Partition - Mark as Active
or for a picture of what you're doing use Partition Wizard bootable CD
Startup Repair - Run 3 Separate Times