That's a good point. Never thought of that. But still if you do that you wont know who is connected to you. They could spoof their mac address, and you could have multiple neighbor's with notebooks. Does the computer connected keep any other kinds of logs of networks it attached to, using say XP?

Is there an application of some sort that will alert computers on a network when another computer joins?
I'm pretty sure that their is. I know they have something like that for netstumbler. With that software it could also email you if someone connects with the details (mac address, date, time, etc..) that way you know something is going on. Doesnt really sound that hard to make. Why isnt this included with most routers?

Keith