people hear that they have, say... 5 megabit download speed internet service.
and they misunderstand that and think that means they can download at 5megabytes
take your megabit speed from your isp,(in thousands of course) and divide by 8.
that would make that guy able to download a single file at a max speed of 625k per second
also remember, not all websites or hosts will allow you to use any bandwidth you want, so it can still be 100k per second if they wish.
and when you download your torrents and music, multiple files have to share that 625k
and multiple computers on that router have to share the 625k also
correct me if im wrong, but i believe thats the math