Airport Extreme set up problem

I have been using an Airport Express for a few years now, but recently the net connection has been dropping out a lot (possibly due to my Linksys router, not the AE). Anyway, I bought an Airport Extreme, but can't get it to work. The connection is fine on my old AE, then I just swap the ethernet cable and plug it in to the Airport Extreme (after setting up using the airport utility cd) but I can't seem to get an Internet connection. The green light is on on the Extreme, so no wireless problems - just no Internet.

I'm using a macbook which I bought in 2007. Does this macbook support wireless N? If not, could this be the problem?

The current set up which works on my old Airport Express is:

PHY Mode: 802.11g
BSSID: 0:1b:63:22:1b:61
Channel: 13
Network Type: Infrastructure
Security: WPA2 Personal
Signal / Noise: -59 dBm / -96 dBm
Transmit Rate: 54

Interfaces:
en1:
Card Type: AirPort Extreme (0x168C, 0x87)
Firmware Version: Atheros 5416: 2.0.19.10
Locale: Japan
Country Code: JP
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 34, 36, 38, 40, 42, 44, 46, 48, 52, 56, 60, 64
Status: Connected

I am currently in Sydney, Aus.
Does anyone have any ideas how to get this working?

Thanks

It may not be the wireless - and it does support n - you can see that in your supported phy modes - 802.11 a/b/g/n

The first thing I would try is connecting your computer with a wire - to the Airport Extreme. If that works then it is a wireless problem. If it doesn't work then your setup of the AEBS on your network is wrong. It would probably help to know all the Internet settings (without giving away anything personal) and all the wireless settings - for both the one that works and the one that doesn't.