Hello Everyone

I'm looking for a network monitoring program. I would prefer that it was free or at least cheap. I want to be able to track my network traffic, bandwidth, and computers on the network; I would also like to see which computer is using up the bandwidth. I am running a windows XP network. Ive tested several that are out there (used Google search), but I didn’t find what I was looking for. Has anyone here heard of or used such a tool? Thanks