I need a freeware to monitor my internet activity, especially upload and download amounts over time. For instance, I like to see a graph or table that shows the downloaded and uploaded amounts per day, week or month and in total for a selected period.

OS: Windows XP, Vista, 7

Edit: I don't need to see the traffic program by program. I'm not interested in which program accesses the internet, but I'm interested in monitoring my incoming and outgoing data amounts using a light-weight freeware.