I needed to do the math today, so here it is. If you only have a line speed of 128 k/s it would take two hours and sixteen and one half minutes to pass one gigabyte through your connection in the best of all situations.
Kilobytes in a gigabyte (1024^2) = 1048576.
Number of seconds to download the 1 gigabyte file (1048576/128) = 8192
Number of minutes (8192/60) = 136.53
Simple enough. In reality, the line speed is more like 85 k/s.