[font=Georgia]Well, I use Linksys as my router. When I access my wireless control panel, I can view the DHCP client table, which shows the active IPs on the router.[/font]
Not always so. The DHCP list will only show you users who got an IP from the router. If they set up a manual IP with the gateway to the router, they will NOT be on that list. I know, because I was jackin some guys connection, and he had a Linksys WRT54G, and I set up my IP to be 192.168.0.111 (I also needed a static IP to open my Bittorrent ports so I could piss the RIAA and MPAA off on his connection ) and I wasn't on the DHCP list. He couldn't get rid of me because he had no idea I was there.
On some routers, such as most NETGEAR routers (notably the WGR614) there is an option "Attatched Devices" that will show ALL of the computers connected, even those manaully configured.
My advice is, if you want to keep someone out, WEP or WPA, non-default SSID/password, MAC filtering, hide your SSID and maybe even use FakeAP. And do a google for "The Definitive Guide To Wireless WarX'ing" by Slayer and read it. Near the bottom there are some security guidelines.
And oh, BTW PeOfEo... that pinging won't always work either. If they have a software firewall, your pings will just get blocked, and it will look like there is nobody there. Same with the Network Places thing.
You guys think that you are seeing everybody, but in reality, you might not be. Esspecially with those linksys routers where you can only see DHCP clients, and not manual clients. As far as I know, however, you can't hide from the Netgear "Attatched devices" list.
And if someone is going to jack wifi access, Linksys WRT54G's are the best to get, because you can hide from the list, and you can also flash their firmware with HyperWRT or any of the other custom firmwares and up the sig. strenght which will allow you to get a better signal. Plus, if there are other people freeloading off of it, and you can figure out who the legit owner is, you can block everybody's MAC but yours and the owner's, and split the bandwidth 50/50.