Unexpected DHCP Clients on Secured Wireless

Hi All.

I have a D-Link DSLG604T wireless router.
Upon sitting on the couch this afternoon I did the usual and checked emails etc.
Whilst not using any traffic, I noticed the router wirelss and ADSL leds flashing away. Hmmm.

I logged into the router and found the DHCP server had assigned two new IPs as I have reserved two other IP for my partner and my laptops.

I opend up windows networking on both machines (Vista home on mine) (Xp home on my partners) and found 3 extra machines. I tried to browse these without success.

I therefore went back to my router and changed the WEP key, and also added the unknown machine MAC addresses to the wireless management access lift as DENY.

I could ping only one of the two IP's with sucess.

I was wondering how to browse these machines to find out who they are etc, apart from using the windows networking browse thing, I dont know.

Anyone else have this happen?
Thanks.

WEP is fairly simple to hack, there are many easy tutorials about it on the web. If your equipment can all handle it (some older cards cannot) try WPA.
I personally use WPA/PSK (preshared key) and it didnt have to be a sequence of numbers as the key. (Easier to remember).
I also have always used mac filtering. People can still easily spoof (pretend to be) a mac address, so it alone is not a healthy choice. Combined they work well.
I'd leave well enough alone with browsing the other computers. If you can see them, they can see you and well...if they've hacked in, theres no telling what else they could/would do.
Try changing the name of your wireless router to "I am watching you"

change your DHCP IP range to only allow the 5 clients you currently want. router will then disallow any more than the clients you have. Could also change DHCP to static and clearly specify the IP's for the clients you DO want.

Or slide me $500 and I will drive to your area, find the buggers with my wardrving rig and rough them up a bit

$500!!! geez we're in a recession ya know!