Whenever my browser wants to download data, I want it to be granted as much of the bandwidth as it wants, while other applications must do with the leftover bandwidth; and when the browser is not transferring any data, other applications could be given the bandwidth. Something like the process priority in Windows task manager. Any method/software to accomplish this automatically?
Both applications do exactly as you want, but they're not freeware. NetBalancer unregistered version may be of some help despite the limitations:
However, if you use WinXP you are lucky, since there's still a freeware named TrafficShaperXP. Another way of traffic shaping/balancing is your ADSL's router QoS menu which is an entire diffenent approach & topic.