A good 'background downloader' - I currently use FDM - allow you to run a download of any size in the background, or just walk away.

FDM will allow

1) auto shutdown PC (and/or hang up dialup modem) when finished.

2) auto restart of an uncompleted transfer (if the server allows it) over multiple sessions.

3) auto priority of multiple simultaneous downloads ads well as shunting dnld rate up and down while using the web browser.

4) splits a large file into several simultaneous 'channels' - this means that the total throughput can be the max of your connection - sometimes individual 'channels slow down and speed up -this is just the way the net works.

5) dialup or broadband.

6) runs thru any firewall.

I did discuss this in another thread here a while ago, but can't remember the link. They now have un updated free version.