If you can access the router via a wired connection AND you can get on the internet with it, there is still hope.
Do you have full connectivity when using the wired side?
You might try turning off the WEP or WPA and having no security to begin with. Once you have connectivity, start adding security into it.
If the Netgear uses some form of proprietary speed enhancer, connect to it via a wired connection and set that feature to OFF.
Make sure that the wireless side is set for 802.11b/g
I would be concerned that it did not also work easily with Vista.
BTW, I'm reasonably sure that your OS is 10.4.x as 10.5 is not due out until next month. Hey, you could be a Beta tester though.
P
I have a MacBook with OS 10.5 and I can not get on the internet. I have a new Netgear WNR834B router (cable modemn). Airport sees the router, and I can 'access' but I have limited conductivity. (The system is set up with a simple 64-bit WEP encryption.) I had to contact Netgear to help set-up my wife's MS Vista. There we had to change the 'Key Index' to 4, from the default 1.
I have tried to reload the system with no luck. (I can access the router through a hard line.) Is there any ideas?
Thanks

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic