I've tried a lot of so called accelerators but Download Accelerator is the one that does it for me. It does what it says, accelerates downloads without all the gizmos, and believe me it's fast.
Installation is simple, just unzip and set up.
Configuration is as easy, just set default directory where you want to save to and enter proxy settings if applicable and that's it. Download Accelerator then sits quietly waiting in the background, no tray icons, no gizmos and fires up as soon as you start to download. It supports resume and can be set to regular download with one click. It's usually the simple things that are brilliant.