Since you have a Seagate in the mix, I'd clean up C and clone it over to the SSD using Acronis' superior free Cloning/Imaging app which comes free with Seagate: Seagate Acronis cloning free util
The Manual is there with the Download and is easy to understand. Use Auto clone to resize to the SSD space.
After cloning set SSD to boot first in BIOS setup. If it won't start, unplug all other hD's and peripherals, mark SSD Win7 (or it's 100mb System Reserved) partition Active, then run Startup Repair - Run 3 Separate Times
After Win7 on SSD is running fine you can copy (not move) your User folders to HD if you need the space, then link them back to Win7 using the related Library - Include a Folder - Windows 7 Forums
To clean up C best use the tools and methods in Clean Up Bloatware