Hi,
I have a Netgear WNR2000 but it's the same basic configuration.
Firstly you cannot extend the Netgear with an Airport Extreme with WDS, Apple's WDS only works with other Airports. However you can do the following:
1) Disable Netgear WiFi - see the manual:
http://www.downloads.netgear.com/files/GDC/WNR1000V2/WNR1000v2_UM_19NOV2009.pdf
See Figure 1-11
2) Connect an Airport via an Ethernet cable to the NG router, configure it to run as "Create a Wirless Network" and in the Internet tab set Connect using: Ethernet and Connection sharing: Off(Bridge Mode)
3) The extend to another AP if required via WDS, Wirless mode: Extend a wireless network, Internet Tab: Connect using: Wireless Network and Connection sharing: Off(Bridge Mode)
Regards,
Shawn