hi, i need some help with people leaching off my wireless network =-P

i have a belkin router with my connected to it, and another one in my house.

currently in the dhcp list it says there are another 4 people connected to this network.

i have also used netstat with DOS and it says that there are 7 extra people connected to the network.

my question is, is there any way for me to find out who these people are, and for me to block them from stealing my network =-P

thanks very much in advance