bandwidthinternetnetworkingwindows
When you use Process Explorer and minimize to tray, The icon turn itself in a graph of CPU utilization. I want to see that graph for network usage, specifically for internet usage. Example, I can download up to 100kb/s. I'm downloading an program at speed of 25kb/s, then I want see the graph with 25% of use of internet usage.
There is a simple and free program like this?
Edit
I've found an "revived" version of FreeMeter here:
FreeMeter Revival
To analyze which device is generating/receiving the most traffic you are going to need network equipment that can collect these statistics.
As mentioned in a previous answer the easiest way to do this is with a managed switch which will allow you to poll the traffic on each port.
Another method is a router that can either collect traffic accounting data on a per MAC address level or export network traffic in "NetFlow" format which can be analyzed by a tool such as NFSen
The final method is going to be installing some sort of packet sniffer (e.g. a PC running Wireshark). In order to get this to work on an unmanaged switch you will need to either install the sniffing PC in-line to the traffic (i.e. two network cards configured for L2 forwarding) or install some form of Ethernet tap between the switch and router.
The less managed network hardware you have in the network the more networking knowledge you will need to collect the statistics.
Best Answer
Check out this article that mentions FreeMeter Bandwidth Monitor For Windows (http://sourceforge.net/projects/freemeter/) and then several more in the comments.