The error is the free Easeus doesn't come with a boot disc.
You can't move system files with the windows GUI while you are booted into the o/s partition, neither can you move them on the System partition that way.
There is a bootable partition manager attached to this tutorial: Dual Boot using free partitioning software - Vista Forums
If you post a screenshot of Disk Management we can advise how to proceed, like this:
Also , do you need to keep your existing 7 installation, or would you be happy to reinstall after reorganising the partritions.
You don't have to reinstall, you can keep both installations by repartitioning and shifting - it's just a couple more steps are needed.