The netgear should not work like that..
It should divide bandwidth according to demand..
Only the higher end routers have throttling. I doubt a low end netgear will have it.. unless it has 3rd party firmware and is setup badly.
Wireless though is never a cut and dried easy to understand.. actually follows the rules technology.. it is 80% voodoo.
You can certainly try the airport in bridge.. it will help even if you simply offload some of the clients from the netgear so use both at once.