PCs on the network only connect to Google

I'm having a rather odd issue. The wireless internet at my parents' house doesn't seem to work for Windows. My 2008 MacBook Pro running Snow Leopard and their 2011 MacBook Pro running Lion can access the internet wireless without any problems. My iPhone 4 also works fine when using the wireless internet.
However, my brother's Dell Inspirion running Windows 7 and my same 2008 MacBook Pro running Windows 7 through Boot Camp cannot access the wireless internet properly. On Windows, in both Chrome and Internet Explorer, we can only access Google sites (Google, Gmail, YouTube, some Blogger sites, etc.) The Windows computers can access the internet properly when they are wired directly to the router, but not over the wireless network. My computer works fine in both operating systems on the wireless network in my apartment, and my brother's computer works fine on the wireless network in his home, but here we're both having trouble.

Anyone have any ideas of things to try?