If you're running Windows 7, chances are you've had IPv6 turned on by default, for a multitude of reasons (incompatibility with certain products, security concerns etc) you might want to turn it off, and it's really easy to do so:
1. Open the Control Panel
2. Click Network and Sharing Center
3. Click the connection that you want to edit - this will then display the status of that connection
4. Click Properties - This will then show the properties of that connection
5. Simply untick the box next to Internet Protocol Version 6 (TCP/IPv6)
6. Press OK
And that's all there is too it! IPv6 is now turned off for this connection.