No Internet Access - Wireless router/network connection problem

I cannot connect to the internet after installing Windows 7 64 bit. I can see the wireless router/network from my computer, but sometimes it gets Limited Connectivity or it says Connected but with no access to the internet. I have used the diagnosis tools on Windows to try and fix it but it doesn't work, and my router is definitely connecting to the internet as I am using it right now on a laptop that's on the same network. I would love to know if anybody else is experiencing this problem and if they have fixed it. I tried changing the Physical address of the LAN connection but it didn't work, I'm guessing because I'm connecting via wireless and not wired, and I have heard similar stories from other forums that this may be a more common problem than I suspect. Thanks in advance for your reply, and any details you need I'll try my best to provide them.