hi,
it's really a matter of most filesizes being quoted in kilobytes, wheres modem transfer rates etc are quoted in kilobits / second. so, if you have a 56k modem, to get the transfer rate in kilobytes / second, you need to divide 56 by 8 (=7!). then to get the time required to download, say, a 1MB file, simply divide 1024 (1MB = 1024kB) by 7, which gives a result in seconds.
note that a dial-up modem will not connect at 56k, maximum is around 53k i believe.
here's a useful link -
http://www.allwindows.com/modemtimes.html
