New
#11
You don't have any choice but to use 3rd party to resize Win8 to the left. We recommend free Partition Wizard bootable CD which has helped here resize countless thousands of complicated partitioning operations without a single failure - whereas all other managers (including PW Home version) except for Disk Mgmt can fail with data loss.
So you'd shrink Win7 in Disk Mgmt: Partition or Volume - Shrink
Then you'd boot PW CD, follow these video steps to resize Win8 partition to the left: Partition Wizard Resize Partition - Video Help.
If for some reason Disk Mgmt doesn't give you enough shrinkage, use PW on Win7 to resize from the right.