I find that one of the biggest factors in download speed (other than your connection speed, obviously, particularly dialup-vs-broadband) is how efficient the server you're downloading from is. Some are terrible -- from MS or Mozilla, I'm lucky to get 6 or 7 KB/sec average mostly due to long pauses when nothing at all is coming in.
But with a really good server which permits resume (necessary to get the benefits of multiple sections, e.g., with Free Download Manager), I can typically get 25-30 KB/sec per section (probably my ISP's limit), or up to 250-300 KB/sec total depending on how many sections the download site will permit. In practice, I'm getting just about a 60x improvement over my old dialup, and can count on 12-15 MB/min, maybe 18 on a good day, compared with about the same amounts per hour before.