Networking & wireless: Connected to access point but not to internet?

Connected to access point but not to internet?

We have two XP PCs in the house. PC1 (HP Pavilion desktop, XP Pro SP2) is the main unit, connected to a 802.11b Microsoft wireless router with a cable modem connection. PC2 (Dell desktop, XP Home) is the secondary unit, using a USB wireless adapter. I also have a Netgear range extender, which is plugged into the Microsoft wireless router.

Here's the problem: PC1 works fine. A few days ago, PC2 had trouble connecting to the internet. At first, it would only recognize the Netgear router (signal strength: excellent), but then couldn't retrieve addresses like www.yahoo.com. I changed the name of the Microsoft SSID, and then back again; again, PC2 would now connect to either Microsoft or Netgear (signal strength: excellent) but not connect to the web.

I have not made any other changes to PC1's settings. Has the Microsoft router just plain gone bad--eg, is not transmitting a wireless signal anymore?

Thanks,

Adam