Can't renew IP address ... why should one wlan connection work and not the other?

So here's my problem
I recently bought a new Advent 8111 laptop with Intel PRO/Wireless 3945abg. I'm trying to connect to my NTL broadband via a Belkin54g wireless router but keep getting failure to establish wireless connection with error "... following action cannot be completed: Renewing your IP address."
I can connect happily with my old laptop to the same router [hence posting this!] using a Cisco 350 series WLAN card - but not the new one?

What I've tried doing ... without success ...
Turned the WLAN hardware switch ON
Run IPCONFIG /RELEASE and RENEW
Compared settings on new laptop and compared to old > the same
Switch on/off laptop, router
Scoured the internet

Any ideas? ... gratefully received