You must reinstall all programs to a newly installed OS because they write registry keys which integrate themselves into the OS until uninstalled, which is also why they should be installed on the same partition with the OS.
You can separate your data out to another partition so if you must reimage Windows 7 on C because it becomes irreparable, your data is intact, current and waiting on the other partitiion.
I do not recommend Easy Transfer because it can fail and you must try to pry your data out of it. Easier to just drag your User folders to external.
Other steps here to to get a perfect Clean Reinstall - Factory OEM Windows 7