Just make sure you're not both using the same channel. There are 11 possible channels on WiFi, listed by number in macstumbler. configure your router to a number as far away from his as possible
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PB G4 15" 1.2ghz - Pismo G3 400 mhz - iBook G3 500 "Jukebox"
"SawSmurf" G4 500 - Quicksilver G4 Dual 1ghz modding...