Networking Bandwidth

I wish to restrict the Bandwidth to other PC's on my home
network from the shared Broadband Internet connection
routed through My computer. Currently I have four other
computers on a home network - they all have internet
access, what I would like to do is restrict the bandwidth
that they are able to use, as currently my family are
using P2P sharing and this Kills my connection and makes
it very slow, Is there any way that I can slow them down
a little and retain my bandwidth?? If so How?
Many Thanks for any help etc.
Configuration is My PC has two NIC's one for Cable
Internet and the other for the house network. Cable speed
is 1Mb,
Regards,
Paul M