I would like to know an adress where i can buy the AT91SAM7X256-EK board. Like in the example in lwip.

The AT91 site lists the kit http://www.at91.com/Pages/products/EvaluationBoard/SAM7XEK/at91sam7xek.html but does not as far as I can see say where it can be obtained. Maybe a question for the AT91 forum?

Try here:
http://www.atmel.com/dyn/general/contact.asp
and enter your country.

have you tried searching the Internet for AT91SAM7X-EK

I've been searching for this board, but there is an problem in avialability of this new evaluation board. Most webshops seems too receive this product soon, but can't tell when. So I hoped someone could help me.