I'd use the tools in my previous post an just copy everything from C:\ into a folder in E:\BACKUP_C\ (or something similar), use the partitioning tool to remove the C: and reserved partition and leave the D: and E: partition as they are. Then reboot, go into BIOS and reset to defaults, then clean install from DVD or USB.
You should see one block of unallocated space before the D: partition, just select that and install there. Once done rebuild your system from the copied image. Don't just move stuff back, but re-download and re-install where you can.
Forget about antivirus. firewalls or other junk, this is all built in now.