If you have adsl, follow this:
Go to Network Connections
open Local Area Connection Properties
Open internet protocol properties
Check off "use the following IP Address"
Enter this info:
IP Address: 111.111.111.111
Subnet Mask: 255.0.0.0
Click OK
Wait a minute
Open Local Area Connection Properties
Open internet protocol properties
Check off "Obtain IP Address automatically"
Voila, your IP address is changed!