Something to keep in mind... For example, say you are downloading a 700mb video file. Your connected to 14 hosts and say 10 of those hosts are dialup and the other 4 are say T1. If you see where I'm going with this... Basically your only as fast as the hosts your connected to. You could have the Fastest Connection on the Planet, but it won't make any difference.
You can try pausing the download, and some times you will connect to different hosts that might be a little quicker, when you resume.
When the cards are in my favor, I have, and often do, download AVI Files at between 250 - 300kbs.
I only download the larger files 1 and sometimes 2 at a time. Just seems to Bogg down if more than 1 or 2.
Hope all of this makes since