XBOX 360 LIVE - wireless adapter and/or membership

Hey techno A2Kers

OK - confused again about these kids toys

if you have an XBOX 360 and wish to play live - and you get one of these wireless network adapters



http://www.amazon.co.uk/Wireless-Network-Adaptor-Xbox-360/dp/B003VD56L6/ref=sr_1_1?ie=UTF8&qid=1291563598&sr=8-1

which apparently plugs into somewhere and then connects to your broadband... then, do you also need to get one of the cards for a LIVE membership?????

I'm being told you don't need to buy the membership with the adapter but can automatically play live with your mates, but if that's correct, why do they advertise that people who bought the adapter also buy the 12 month membership as a bundle?

Hmmmmmm..... izconfused.com again!

any gamers here who know about this? thankeee