I use dail up for 3 years and never once it went past 5kb/s.
I agree with what martin said entirely, it also does that if you start an unfinished download quickly in IE, (yes IE can resume stuff, but it does it poorly and only works if you do it a few minutes after a download dies).
Another thing that could fool you is compression, Dial up modems and in fact all the internet can send out data compressed as far as I know, I downloaded some file once on dial up and it was going at blazing speed, yeah, it was,
HOWEVER, that was only because the data I recieved was compressed, much like a text file, notice when you download a text file on dial up it is going faster than your connection can go? Compression baby.
I'd test my connection now but I am busy downloading something.
Now, I can go 100kb/s with my current connection, and that is constant. beats any 80kb/s
