Network Adapters

[simonwood]

I don't know if this is the right place to post this but I guess some of you would know anyway.

What is the diff. between the Sony brand network adapter that goes in your expansion bay on the back of the ps2 and the cheap ones I have seen on eBay that just plug into your usb port?

Do they function the same? If they do, the offbrand usb n.a.'s are much cheaper and I would get one of those instead.

Thanks