How can I download one file from different places

"Free Download Manager offers this (amongst many other features):

Simultaneous downloading from several mirrors

Free Download Manager is able to
download files from several mirrors
simultaneously.

Download acceleration

Free Download Manager splits files
into several sections and downloads
them simultaneously, allowing you to
use any type of connection at the
maximum available speed. With FDM
download speed increases, or even
more!

FDM is open source freeware."

This is exactly what BitTorrent does. I would make a torrent and then have the many slow servers seed it.