Dell and Hp are the same thing... cheap systems made in bulk for a company to buy by the 100s so each staff member has the same system Acer is a knock off of Asus and Asus was the best for years but they have stopped putting in the effort they used to so if you are not gaming i wouldn't...
its unlikely to have anything on the C drive... normally that would be stored on a small backup partition with the name 'recovery' [something like that]... have a look in disk manager [windows key] + [x]... wait a sec then press [k] on most systems anyway should you muck about with it = no...