i run a belkin wireless router, my pc is hardwired and the one upstairs is connected with a wireless usb access thingy, ran netstumbler upstairs and had an intruder, i killed my home network and grabbing thier mac addy i blocked it in the router and enabled only my 2 mac addys thru the enable mac filtering function, yet the intruder was still present, i had to go to work but want it locked down when i get home, i need help