Does you family have the same problem connecting to the internet?

Do they connect wirelessly?

Is the wireless side of the Netgear WPN824 configured to use wireless protocols, 11b and 11g?

That router has 4 wired ports on it. What happens when you connect your Macbook to a wired port.
Internet or not?

If yes, then the wireless side of the router may not be configured correctly. Of course, it could also be that the wireless side of the Mac is not correct.
I note you said you were manually switching IP numbers on the Mac. This should be unnecessary if the router and Mac are both using DHCP to obtain addresses.

Who configured the router in the first place?

Have you checked the Router configuration?

Is the router firmware up to date?

Your subject line is misleading. Is the problem that you are the only one that cannot access the internet and that the rest of the family are surfing like there's no tomorrow
or
Is the entire family unable to connect to the Internet, which is what your subject line implies

P