Are there other computers connected to the wireless? If so, it's probably the laptop.
Check for DHCP on the client:
Go to Start -> Control Panel. Open the Network Connections panel. You may need to switch to Classic View to make this easier, I don't recall what it's buried under in the helpful view. You should see the Wireless Connection there. Right-click it and choose Properties. In the middle of the window that pops up, double-click Internet Protocol (TCP/IP). On the General tab that pops up both options should be set to "Obtain...".
If it is set this way or you changed it and it still isn't working (give it a minute if the settings were wrong), keep going and...
Check for DHCP on the router:
Go to Start -> Run. Type CMD and press Enter. This will launch the command prompt. Type ipconfig and press enter. This will tell you how your network interfaces are configured. If the Wireless connection IP Address starts with 169.254 then the router didn't provide it an address. A typical wireless router is set up to offer 192.168.x.x or 10.0.x.x addresses.
If the router didn't provide an address, you could fiddle with settings, or you can reset the router. You'll need a paper clip and 30 seconds to do that.
If you can give us a little more info, it'll make solving the problem easier.