ReGet Pro is good software. It's a download manager for getting large (10MB+) files with some management instead of straight in your web browser. Integrates into Firefox via the FlashGot addon.
I'd always thought download managers were stupid. Their primary advertised feature is downloading several chunks of a file in parallel "for faster downloads". Because of how TCP/IP works this idea is almost always terrible for large files. It only works because you're circumventing the server's bandwidth throttle; that's anti-social.
But ReGet Pro can be configured in a more useful way, to limit bandwidth. I've got mine set up to download only one thread at a time with a max bandwidth of 180kBps, comfortably under my 240kBps connection. That way I can download big files in the background while doing other things on the net. It also turns out that ReGet's suspend and resume function is surprisingly useful; Firefox is suprisingly unstable to be using for 3+ hour downloads.