how to limit download speed of a network user.?

[john]

Shaping with qos is the only thing that you would be able to do unless your router supports a download limit per IP address. If that's the case, then you can assign the same address to the PC that you want to control and then limit bandwidth that way. The only problem is that I believe most support a bandwidth cap instead of speed. That means that it will allow the person to download up to, say, a limit of 2Gb of data, but it doesn't control how fast that data is received.