The problem with downloading via a web browser is that it will saturate all current bandwidth, unless throttled. You can do achieve this by downloading through a download manager or using a download tool such as a torrent client, which can control both the upload and download ratio. For most users, they simply grab Internet Explorer and start downloading.

If you need to control download speeds at your company, then you could setup your a users browser so that it will only take a certain percentage of your bandwidth.

Firefox Throttle is a small tool that you can use to control the bandwidth for a web browser on your network. You can also assign exceptions or control based on a workstation IP.