xbox wireless adapter - router device list

Bit puzzled about an issue I have with son's new wireless adapter for his xbox. It's definitely connected to our router, works perfectly and has a legit ip address but doesn't appear in the list of attached devices in my 2wire router.
Is this normal?
Just seems odd that anyone could be access our network with one of these adapters and not be noticed (asuming they've cracked the security) apart from maybe excess usage.
Do other routers show these adapters?

Depending how your router is setup (firmware wise, nothing you can really do), it might not show unless it has a proper device identifier, if it doesnt it might just ignore it.

i have the same things with my PS3 both never shows up in the router (WNR2000) its not a problem but i suppose would be nice to no why lol.

Ash