If you wanted to shrink C by about 100mb using Partition Wizard Resize Partition - Video Help
then you could extend System Reserved into the space using Partition or Volume - Extend. This worked when there was an issue with SysVolInfo file crowding SysReserved to prevent Win7 Backup Imaging. That issue is resolved.

There is always a risk of boot failure when resizing on the boot sector, however this is easily remedied by running a few Startup Repairs.

A better approach in this case would be to move the Bootmgr - Move to C with EasyBCD - Windows 7 Forums then delete System Reserved and ignore it since it is so small.