Local network throttling?

I was wondering if it's possible to have one or several PCs connected to a network and have them get only a fraction of the bandwidth they would normally get.

a person here's hogging all the connection speed with her p2p shitz without any consideration whatsoever to everyone else.

WRT54G is our router.
and would it be possible to point me to a step-by-step guide on how to do this? Or at least give me the skinny of it all.

gracias!

You can change the QoS settings in that router, give http ports higher priority, port 80, 8080, 20 and 21 too (ftp).

Also any other ports commonly used (for games for example)