Cannot connect to any wireless networks in Vista

Could somebody please help me? I cannot connect to any wireless networks I find, all of which are open access points. Even though everybody around me can connect and use the internet, I can't. In fact, 9 times out of ten lately whenever I attempt to connect, Vista says after anywhere from 5-30 seconds that it could not connect to the network. And the other 10% of the time it connects but it cannot get past the limited connectivity stage so, it is utterly useless. I have tried everything I could think of; ipconfig /release /renew, after restarting the computer, safe mode with netowrking, fiddiling with the advanced settings of the adaptor, turning off QOS and other settings, damn near everything that diagnostics says to do short of resetting the router, which probably wouldn't work seeing as my laptop is the only one that cannot connect. I even tried rolling back the driver to no avail!
My Gateway Laptop has a Realtek 8187B Wireless Card and Vista Home Premium x64, although at this point I really wish Linux had some decent drivers for my wireless card... although at this rate I might be able to get it to connect around the time the 3.0 kernel rolls out. Any suggestions as to how to get this thing to work?

Do you have a firewall running in the background? It seems that may be the issue. Make sure all of your protocols are correct as well. I have a Gateway laptop that works perfectly fine on any WiFi network.

It isn't the firewall

I already tried turning Norton Internet Security 2009 off, and I turned Windows Firewall off as soon as I installed it. Though it didn't help any, Norton never gave me any problems before anyways.