I'm not sure where to post this, so whatever…

I live in a converted 3 apartment victorian house.
I have been sharing my DSL with my housemates for the last few years.
When Leopard came out, the Sidebar would show the shared connections, so I could see who was on when. I liked that.
Through various updates, etc., I have lost that ability. (leo 10.5.8)
Same with MobileMe. sometimes I see my work computer, sometimes I don't.

My question is, shouldn't I be able to see who's on my network and who's not?
It's so sporadic, I can't figure out how to troubleshoot.
Using Airport Express.

I would like to know how much bandwidth they are using and when they are using it.
How can I keep these settings consistent?

I'm to the point where they can just pay for their own connection…