Have you tried to connect to other open wireless networks (local coffee shops, neighbors, whatever...they are everywhere).

If you can successfully connect to others, then I would suspect your router. Netgear is pretty average with regards to their wireless routers, or so I have heard.

If you can't connect to anything, then your hardware may be bad.

I'm assuming that the computer that can connect and your Dell are roughly in the same physical location so it's not a case where you are trying to connect with a microwave between your Dell and your router.