uh..no, a reformat leaves all data there, its just ready to be overwritten with new data is all, why do you think it works so fast? most good recovery software will recover anything from a reformat.
you have to overwrite the data, 7 times is the department of defense minimum standard, 1 overwrite will prevent software recovery, 7 times prevents hardware recovery, if the fbi wanted info off your drive they will get most of it if you dont use at least 7, 35 is the guttman standard, all take much longer than reformat though.
nuke it and boot is a freeware but will do your whole drive, eraser will work in windows and just overwrites deleted data and free space, likely all you'll need.
has drive scrubber, 30 day trial but you only need it once and it works fast.
if you destroy a hard drive the fbi recommended you drill a hole through it, a magnet is not sufficient as its still rotatable and hardware recovery will get alot of data off it, same with burning.