Wireless Connection working...but cannot connect to the Internet!

I just got my Dell Inspiron 1505 laptop on Tuesday.  I set up the network using a Netgear router.  Everything was working fine on Tuesday, and I was able to connect to the Internet.

Yesterday I had my laptop at school, and I connected through the school wireless network just fine.  When I got home, I could not get on the Internet (it keeps saying "Cannot Find Server").  The router is showing the the wireless network is working, and my laptop shows that I am connected to the wireless network, but still nothing.  The only thing I can gather is that it has something to do with a firewall.  When I checked the Windows firewall it was turned off.  The laptop also came with a Trend PC-ilin virus scan that I am not sure has a firewall in it.  The only other piece of information I can think would be relevant is that on my desktop computer that is also connected to the router, it was showing the same Internet error yesterday, and my sister reconnected the LAN by clicking on it under network connections.  So....does any of this sound familiar?  Should I undo the router and redo it?